Wednesday, April 22, 2015

Some non-water related musing


Hi CK,

I just want to join with those to say a "thank you" to you for creating such an interesting blog!  I don't believe we can find the sorts of info you're writing about anywhere else!

You have also provided a certain level of "consumer" info e.g. on alkaline water etc. that is pretty useful to other laymen.  Once again, thank you - I enjoyed reading the articles you have put up.

S


Hey, thanks, S.

It is always nice to hear such encouraging words from my readers.

Being an educator myself, it is always uplifting to have current and former students providing positive feedback to reinforce the fact that what we are doing is right. (Don't be mistaken, negative feedback is valuable in helping us improve ourselves but the pure happiness of receiving positive feedback is irreplaceable.) 

Being humans, there are times when we doubt ourselves no matter how strong our convictions are. Are we walking the right path? Is this worth doing? Are we making a difference?

During those trying times, even a short encouragement or a few kind words make all the difference. And sometimes, our whole future can change from the decisions we make based on that short conversation with a kind soul.

I have been on the receiving end, as well as on the giving end. Sometimes, we may not think much of our own kind acts. To us, it may be the most natural thing to do. But to the other party, it can a virtual lifeline, a way out of the darkness into the light.

Therefore, I consciously try my best to spread kindness whenever possible. Small acts, quick words but the impact can be bigger than we think. And in a way, that is the right thing to do.

I may not be able to bring a whole nation out of poverty into the status of a developed country but I can help others along the journey of life, making a part of the world (no matter how small) a better place than I first encounter it.

I write because I like to. Water and its topics just happen to be what I am familiar with and working on. Education is a tool. Above all is the attitude to share your knowledge and willingness to better our own condition and that of others.

Cheers.

Sunday, April 05, 2015

Why I wouldn't be drinking alkaline (aka ionised) water

A bit long of a post but try to read it fully to get a well rounded story.

Alkaline or ionized water was all the rage some years back in the domestic water category. It hasn't lost it shine though. New and supposedly ever better models are still coming out and sales staff are still fervently promoting the benefits of drinking alkaline water.

In fact, in c2011, I was approached by one company to write a book on the health benefits of alkaline water. Being somewhat skeptical then (and even more skeptical now), I respectfully decline.

Then in c2013, another company approached me to conduct experiments to help substantiate the claims of its ionized water. This time, instead of talking about drinking the water itself, the company is interested in promoting the use of ionized water to preserve food, cooking and preparing beverages. It was convinced that food and beverages prepared as such were fresher, better tasting while retaining the benefits of drinking alkaline water. In this case, I must admit that the request was kind of outside my expertise so I happily pass it along to my food colleagues.

(It should come as no surprise that alkaline water can preserve food well because of its high pH which makes the environment hostile to most microbes, especially if the food is dipped in a large vat of alkaline water.)


So how is alkaline water produced anyway?
It is typically produced in a machine commercially named a water ionizer. One part of the resultant water has above neutral pH (alkaline) of 8-11. (FYI, the pH scale ranges from 0 (highly acidic) to 14 (alkaline).) You can actually make alkaline water yourself (DIY) by adding sodium bicarbonate (just a fanciful chemical name for baking soda) into your water. But since the profit margins for selling baking soda are simply too low compared to selling a shiny and sophisticated machine like a water ionizer, no self respecting company will want to mention the possibility of DIY to make alkaline water.


[Start of tech talk]
Back to the water ionizer... it makes use of electrolysis - passing an electrical current through water between 2 electrodes - 1 positively charged, 1 negatively charged. In simple terms, positively charged ions (cations) like calcium and magnesium migrate to the negatively charged electrode (cathode) while negatively charged ions (anions) like sulfate and chloride migrate to the positively charged electrode (anode). The cathodic region becomes alkaline due to reactions between the cations and water and no surprise, the anodic region becomes acidic due to reactions between anions and water.

To further prevent the cations and anions from coming together again, ion selective membranes (a really thin film with special properties) separate the cathodic and anodic regions, allowing ions to pass only in 1 direction. In proper technical speak, the whole process should be called electrodialysis (because of the membrane) rather than electrolysis but I suppose electrolysis sounds easier to digest for most sales people and customers.
[End of tech talk for now]

Lots of water ionisers come with filters and other water treatment accessories e.g. activated carbon. To me, they complicate the issues regarding alkaline water. If you become healthier after drinking alkaline water, is it because of the alkalinity itself or is it because the water is cleaner after filtration? Nevertheless, I will focus on alkaline water per se in this post. You can find out more about water filters in my other posts.


How does alkaline water benefit you?
If you read up on the advertised claims of the suppliers, alkaline water can:
  • delay ageing
  • counteract cancer
  • detoxify
  • lower blood cholesterol, sugar and pressure
  • remove stones
  • prevent arthritis
  • weight loss
  • improve energy levels
  • keep heart, liver, bones healthy
  • probably improve lots of other health issues you can think of
What a list! Don't get me wrong, there are indeed things that can improve many aspects of your health. Think of exercise for example. Exercise can do all of the above and more. It makes me wonder why some people are not doing it. Maybe they prefer to buy a quick fix like a water ionizer. After all, drinking ionized water does not come with the hassles of spending time and effort exercising and getting all sweaty and uncomfortable.

Naturally, I am skeptical when a commercial product or service comes with more beneficial claims than snake oil. After all, how do you effectively prove so many claims. It is not easy to do scientifically robust studies to prove a single health claim. You need time to do that. For example, drugs can take years or more before they are allowed to be sold on the market. The gold standard will be clinical studies of patients involving double blind experiments. You don't see that with alkaline water (and lots of other health supplements). Yes, I know drugs are different from alkaline water but the health claims are no less serious and in many cases, alkaline water sounds more omnipotent than any drug.

And in some cases, the suppliers use BIG words like "miracle" water. This really sets off the BIG warning alarms in my head and have me recoiling with BIG question marks.

Eventually, what you often see are "testimonials" from "satisfied" customers. "After drinking alkaline water form XYZ brand, I feel healthier... I no longer suffer from health problem ABC... At first, I am unsure but after trying it out, I am a true believer." I bet you see roughly the same testimonials as above more often than you care to count. In a way, they are selling hope but what you don't want is when hope and reality don't meet.


Say WHO
By now, I can hear some of you asking what does WHO say about pH in its drinking water guidelines. Well, in WHO 2011 edition, there is no recommendation for pH as it is not a health concern though Singapore's Environmental Public Health (EPH) regulations stipulate a pH of 6.5-9.5. I believe this range is more for protection of piping and equipment against corrosion in too acidic or alkaline an environment.


The Science behind the scenes
Sometimes, scientific theories are presented out of context. Yes, acid and alkali neutralise each other. So if you body is too acidic (bad for health), simply drink some alkaline water to achieve balance again. Simple, right?

If you believe that, maybe you also believe that you can remove your brain from you body and hook it up with wires and electrodes in a nutrient vat so that you can live beyond the demise of your body. (Just kidding) Unfortunately, our bodies are really complex machines. What works in a vat usually does not work in the real body with its many biochemical/biomechanical operations interacting in ways many times as yet not understood.

Figure: An interesting and ultimately unanswerable question: "How do you know you are not a brain in a vat somewhere and your whole reality simply fed into your brain via electrochemical/biochemical signals?"


Take pH for example. Human blood pH is an average of 7.4 (slightly above the neutral of 7). Drop below 7.35, you get acidosis. Go above 7.45, you get alkalosis. Both conditions can lead to serious health complications. The reason why human (and animal) blood needs to maintain such a stable pH is because pH is often quoted as the master parameter in any system, be it human body or a pond. It affects how chemical and biochemical reactions will play out. A different environmental pH will lead to a different reaction pathway, giving rise to different products. Or the reaction may not even proceed at all.

So why are people talking about the body being too acidic? The body will automatically correct the blood pH within the narrow range of 7.35-7.45. (WE are talking about blood pH here. Saliva and urine will have a slightly different pH range. Stomach pH IS acidic - see below. Healthy fetal blood pH is also slightly different.) How in the world is alkaline water helpful?

For those who remember your biology, stomach pH is acidic, say 1.5-3.5. You need this level of acidity to properly digest your food and to kill off many pathogens. (IN chemical terms, the acid is to break up the chemical structures of foodstuff like proteins so that your digestion enzymes can do their work on the fragments.)

IN case you are worried that drinking alkaline water will neutralize this acidity, good news - a healthy stomach can automatically compensate for such actions and retain it normal pH range. So my point is - when you drink alkaline water, it ends up mostly in your stomach where it is neutralized by your stomach acids. How are its benefits supposed to be transferred to your body??? (FYI, once your acidic stomach contents reach the small intestine, bicarbonate is secreted to neutralize the acids so that the acidity does not travel further down your system.)

Lastly, if anyone reading this feels strongly about alkaline water being really vital for health, please do not flame me and just go ahead to drink it if it makes you feel better. This is after all a free society. As for me, I will keep alkaline water at a distance. More often than not, we just need an adequate dose of good old plain water to function efficiently at optimum health. Keep this a priority before you open your wallet to other "healthy" options.

Figure: If you find yourself feeling lethargic, sometimes all you need is to hydrate yourself. Above is my favourite type of water bottle - stainless steel. Tough, no chemicals to leach and possible to use it for boiling the water if necessary.

Sunday, March 29, 2015

Enough clean water for my children and their children - remembering Mr Lee Kuan Yew (LKY)

This week (23 - 29 Mar 2015) marks the mourning of the passing of our first prime minister, Mr Lee Kuan Yew (LKY), widely recognised as Singapore's founding father.

As I was going through the historical documentaries of the man shown continuously on TV, I was reminded of his contributions to the water supply in Singapore. The early years of Singapore (1960s, 70s) were trying times. Massive issues had to be resolved right there and then - housing, education, healthcare, security, jobs and of course water and sanitation. It was mind boggling to contemplate these issues all together, much less come up with workable solutions.

Anyone familiar with human nature should realise that once the basic human needs (e.g. food, water, shelter) are not met or disrupted, you are going to have lots of trouble on your hands. Think about looting, rioting and general social unrest - just look at Chile, Haiti after earthquakes. I am sure there are many more such examples if you google them up.

No, in the chaotic situation that is Singapore in the 1960s, water needs must be effectively addressed. (Sanitation too as I believe water and sanitation are merely 2 sides of the same coin hence the term, watsan but sanitation is a story for another day.)


http://www.pub.gov.sg/water/memory_LKY/Pages/default.aspx:
'In 1963, just a few years after its self-governance was declared, Singapore experienced a severe drought. This harsh experience left a deep mark on the population. As the Prime Minister of Singapore at that time, Mr Lee Kuan Yew was determined to drive Singapore towards water sustainability. This, he did by making water a top priority in government policies. "This [water] dominated every other policy. Every other policy had to bend at the knees for water survival."'

In those early days, LKY already realised that there would not be enough water given the paces of development and population increase. Water from reservoirs and from Malaysia were not going to make it. (Only MacRitchie, Pierce, Seletar and Fort Canning (for the port) were operational as of 1963. Source: PUB) (As of the 1960s, the very first agreement signed in 1927 was no longer in force. 2 others - 1 signed in 1961, another one in 1962, were then operational. Source: Singapore Infopedia)

Looking at the scene now (2015), I am quite pleased to see the 4 National Taps operating - local catchment, imported water, Newater, desalted water. By 2060,
  • Total local catchment area will have increased from the current 2/3 to 90% of surface area (see previous post related to this topic)
  • http://www.pub.gov.sg/about/historyfuture/Pages/WaterSupply.aspx:
    "Currently, NEWater meets up to 30% of the nation’s current water needs. By 2060, we plan to triple the current NEWater capacity so that NEWater can meet up to 55% of our future water demand."
  • http://www.pub.gov.sg/about/historyfuture/Pages/WaterSupply.aspx:
    "Today, desalinated water can meet up to 25% of Singapore’s current water demand. The plan is to grow Singapore’s desalination capacity, so that the Fourth National Tap will be able to meet up to 25% of our future water demand by 2060."
  • What is so special about 2060?
    http://eresources.nlb.gov.sg/infopedia/articles/SIP_1533_2009-06-23.html:
    "Beyond 2061The Singapore government has stated that it will not renew the 1961 agreement which expires in 2011. Attempts to reach a new deal with Malaysia to secure water supply for Singapore beyond 2061 have not borne fruit despite years of tedious negotiations. To reduce Singapore's dependence on imported water, the government has taken steps to increase the size of the local water catchment area and to build up the supply from non-conventional sources, namely NEWater (reclaimed water) and desalinated water. With the various water projects progressing well, government officials have assured Singaporeans that the country can be self-reliant in water by 2061 if it needs to be."

    Yup, so that is it. The last 20% will be served by local catchment by 2060.
With such forward planning, I feel assured that the water needs of the country and my family will be well met...

But... (there's always a but) all these come at a price. Newater and desalted water are not cheap to produce. Requiring sophisticated reverse osmosis units using easily fouled membranes, they basically involve passing contaminated water through a filter that removes the contaminants. Imagine a filter with really small holes that only allow water molecules to go through. Even small stuff like salts and oils are retained on the filter. This is going to use lots of pressure to push the water through and  associated with it are high energy usage and costs.

https://www.cscollege.gov.sg/Knowledge/ethos/Issue%202%20Apr%202007/Pages/Water-Management-in-Singapore.aspx:
"The first year (2003) tender price for NEWater from Singapore's Ulu Pandan plant was S$0.30/m3, which is significantly less than the cost of desalinated water. The selling price of NEWater is S$1.15/m3, which covers production, transmission and distribution costs."

"The cost of the desalinated water during its first year (2005) of operation was S$0.78/cubic metres."

Desalted water is naturally more expensive to produce than Newater because seawater is much more saltier ("contaminated") than normal wastewater in our sewers. As such, you need much higher pressure (translated into energy and cost) to filter off the salt in seawater.

In contrast, the production cost of tap water should be in cents/m3 (sorry, can't find a good source for this figure. I picked it up when I studied about reverse osmosis in university.)  

Finally, don't forget that to ensure water security for our small nation, energy security is a co-requisite. Without natural gas, biofuel or whatever to generate electricity, desalination and Newater production will be adversely affected.

Thursday, March 26, 2015

The curse on the waters off Pasir Ris

The waters off Pasir Ris seem destined to be cursed with massive fish kills now and then. Fish kills have been documented there for years! (See my previous posts on this topic.) The latest came as no surprise - Straits Times 1, 2; Today 3, 4; Channel News Asia (CNA) 5.

In response to an invitation from CNA to check out the waters there, a team of us headed down to the field for a quick water quality monitoring (WQM). It had been a week since the fish kill occurred so I was not expecting to see anything extraordinary in our WQM results. Nevertheless, it was a good chance to stretch those hands and legs on some good old field work.

Other than conducting field trips for my students as part of their curriculum, it has been some time since I have field work in WQM. For those following my blog, I had been involved in other aspects of water the past few years - rainwater harvesting, grey water recycling. Water is such a fascinating yet vast topic. It can cover indoors, outdoors, natural, industrial, agricultural, household, economics, political, war and many other areas besides.

Back to Pasir Ris... On 10 Mar 2015, we did WQ tests at 2 spots at Pasir Ris and 1 spot at Punggol for reference. Here is a summary of the results.



The number above may appear intimidating but worry not, below is a description in plain English.


Overall, the water quality looked pretty good for all 3 locations. A few points:

1.       The water at Pasir Ris has become somewhat saltier compared to my data in 2010.

2.       The water has also become somewhat more alkaline compared to my data in 2010.

3.       The water is significantly clearer (less turbid) compared to 2010. Less construction work going on?

4.       Nutrients (ammonia, nitrate, phosphate) are significantly less compared to 2010.

5.       Bacterial counts are significantly less compared to 2010. Can we all swim there now?

6.       Pasir Ris spot 1 appeared to have a slightly higher bacterial count compared to the other 2 locations. FYI, spot 1 is where a great deal of dead fish were washed up the previous week.

 Don't forget, about a week has passed since the fish kill. Don't expect to see problems in the water quality during our field trip or we will still be seeing dead fish on the shores for the entire week - a scary thought.

Figure: WQM team at work at Pasir Ris

Figure: The cozy CNA van that brought us and our equipment around our test sites

Tuesday, March 17, 2015

Fluoride and other contaminants in beer


Hi there,

I've browsed your blog many occasions and always found it a good read, irregardless of whether it answered a question I had at that point in time. 

A bit of background - Water is something key to my interests, as I have grown up with freshwater fish and currently have become a brewer(of beer). Therefore chemistry and quality of the local liquor has always concerned me. 

I have recently installed a water filtration system at home with activated alumina - with the intention of removing fluoride. Would you have any advice on where I could get a water test done up? Key substances would be chlorine, chloramine and fluoride. Also, I'd be open if you have other advice to share.

Best regards,
E


Hi E,

Thanks for sharing your interests and your thoughts on my blog.

You have touched on one of those controversial and hotly debated health topics in water and food - fluoride. Fluoridation of drinking water was initially touted as beneficial to the protection of teeth against decay. Over the years, studies have shown that an excessive amount of fluoride in our bodies can lead to fluorosis which affects the teeth and bones adversely. The irony is not lost to most people aware of this issue - too little fluoride, you get tooth decay; too much, you get teeth damage.

More about fluorosis in this WHO (World Health Organisation) page or feel free to google up yourself:
"The dental effects of fluorosis develop much earlier than the skeletal effects in people exposed to large amounts of fluoride. Clinical dental fluorosis is characterized by staining and pitting of the teeth. In more severe cases all the enamel may be damaged.

Chronic high-level exposure to fluoride can lead to skeletal fluorosis. In skeletal fluorosis, fluoride accumulates in the bone progressively over many years. The early symptoms of skeletal fluorosis, include stiffness and pain in the joints. In severe cases, the bone structure may change and ligaments may calcify, with resulting impairment of muscles and pain."

Naturally, one BIG question is what constitutes an excessive amount. Remember, our intake of fluoride includes the food we eat too. There are already arguments against fluoridation of drinking water since it is claimed that the dosage from our food is already enough to fight tooth decay. According to the drinking water guidelines from WHO, the limit of fluoride stands at 1.5ppm (parts per million). And based on the Singapore Drinking Water Quality Report 2014 from  PUB, our drinking water has an average of 0.48ppm and a range of 0.40-0.62ppm fluoride.

For people concerned about fluoride, filters containing activated alumina have been well known to remove fluoride. Back to answering E's question, my concern is given the already low level of fluoride in Singapore tap water (see previous post, Evaluating the necessity and usefulness of water filters for domestic tap water for an idea), how effective is your filter in removing fluoride? I was going to ask whether there is a need to remove the already low levels of fluoride but since you have already installed the filter, this question is moot. :-)

If your intention to test for fluoride, chlorine and chloramine is one-off, then you can approach a commercial testing lab. The ones I know are (in no particular order):
  1. Tuv Sud PSB
  2. SGS Testing
  3. Setsco Services
  4. CPG Laboratories
If you only have one water sample to test, I believe your tests should not cost more than a hundred dollars. BUT very importantly, do find out the detection limits for their tests. If the test results show zero, they simply mean that that particular contaminant is NOT DETECTED rather than totally absent.

On the other hand, if you intend to conduct these water quality tests on a long term basis, you may want to consider getting a test kit such as the Checkit Comparator from Aqualytic. The Local distributor is Quantum Technologies Global Pte Ltd. It is designed to test for fluoride from 0.2-2ppm. I feel that this should be enough for your purpose. To detect any lower concentration will require more complicated (and expensive) instruments normally found in a lab. And frankly, I am sceptical that there is a need to reduce the fluoride concentration any lower for beer. Not to mention that it may not be economical to do so - you will need technology more advanced than filters to achieve that low a level.

Similarly, the Checkit Comparator can also test for chlorine (free chlorine ) and chloramines (combined chlorine). But do note that each of these tests require the use of different chemicals. Please be careful about storage, handling and disposal. Wear protective gear and make sure other people are not unnecessarily exposed, especially children.

Figure: Aqualytic Checkit Comparator. Different coloured discs are used for different tests. The above discs are for nitrate (pink), ammonia (green), phosphate (blue).

Saturday, June 28, 2014

Rainwater harvesting in HDB flats? Check out Treelodge @ Punggol

I had the privilege of given a tour of Treelodge @ Punggol by HDB staff some time back. The tour includes a sneak review of the various green implements on the rooftop (normally locked from the public) of this housing development.

Of particular interest to me is the rainwater harvesting system. Some highlights:
  1. Rainwater is harvested from the rooftop, treated and channelled into storage tanks at the top level.
  2. Grating is installed at inlets on the rooftop to remove large contaminants e.g. leaves, litter
  3. The system is designed to make use of gravity to minimise pumping.
  4. A first flush system is used to remove the first portion of each rainfall event. (As mentioned in my previous posts (1, 2), a first flush device or system is absolutely essential to remove the initial and dirtiest portion of rainwater.)
  5. The treatment of rainwater involves something called DPA system or technology.
    • "proprietary technology which harness on the works of Hydrocavitation, where liquid is subject to forces of fluctuating pressures within the enclaves of its cavitational chamber, is a chemical-free water treatment process.
    • DPA system is effective in controlling pH levels, increasing dissolved oxygen and significantly reducing bacterial and algae growth in the water."
    • Installed by a company called Sif Eco Engineering Asia. Tried to visit its website at www.dpasys.com but ended up at a page under construction so I don't know anything more about this company. 
  6. Not surprisingly, the treated rainwater is only used for:
    • Washing of staircases, void decks, corridors
    • Irrigation
  7. Obviously, potable use of the treated water is out of the question. Neither is it used for toilet flushing.
  8. No mention of how successful the system is but I don't think there are any problems. Rainwater is one of the cleanest forms of water.
Figure: Garden beds on the rooftop. Nice touch. Cool the top levels?

Figure: Experimental wind turbine. In Singapore, you have to go high for wind turbines to capture the energy of the stronger winds.

Figure: Photovoltaic (PV) panels on the rooftop to provide extra juice to power consumption in the common areas

Figure: Explanatory panel on the rainwater harvesting system. Unfortunately, this panel is on the rooftop so the public normally does not read it. Not sure if there are similar panels in the accessible areas.

Figure: Notice the grating inlet fixed into the floor (rooftop). It is designed to filter off the gross (in size) contaminants in the rainwater. Also, notice the small white pipes jutting out of the garden beds. The plants probably help to clean up the rainwater a bit before channelling it to the inlet.

Figure: Treelodge @ Punggol

Sunday, June 22, 2014

Advice on purchasing water testing kit for JCU Singapore

I found your blog online whilst looking for water testing equipment. I hope you don't mind me contacting you! 

I am a sessional lecturer at JCU Singapore and teach a first year subject called Environmental Processes and Global Change. It is essentially an introductory amalgam of geography and ecology. I take my students on at least two field trips (and a 3rd if we have time and the weather is kind to us!) Last year, for one trip, we went around the corner to Bishan Park to do a number of activities, including water quality testing. The kit I used was borrowed from (removed by blog owner) and was really far too basic for our needs (although none of the students had ever done ANY field work before so it was still fun). I would like to order a kit for the department (we don't have one yet), preferably one that has a number of options and could be used for other subjects (e.g., marine science, aquaculture etc). 

Do you know of a brand / local supplier you could recommend? Ideally it would be robust (come in a lightweight case) and give accurate enough data to compare DO, pH, salinity, temp etc between locations. I have found a kit online from a company based at Ubi Ave (bksna.com.sg), but would appreciate any recommendations or advice before I go any further!

It would be nice to touch base with you anyway, as it seems we may be teaching similar subjects.

Kind Regards,
M


Hi M,

Glad to see that you bring your students for field trips. I always believe that our students don't go out of their classroom enough. There are of course logistics and safety to be concerned with but something suitable can usually arranged.

Previously, I minimise mentioning about companies, brands and models as I don't want to be seen to be endorsing them. However, there had been many requests from my readers to recommend vendors and equipment to them, whether for water filtration, water quality monitoring (WQM) or water engineering. I realise that I am doing a disservice to you by withholding such information.

But first my caveat: throughout my blog, any recommendation of companies, brands, models is purely based on my experience and knowledge. Unless stated explicitly, I am in no way affiliated to them and derive no benefits from recommending them.

You may want to read my book "Your first guide to water quality monitoring in Singapore" for a description of the WQM equipment that I have used. It is available online free at PUB's website.

There are actually many distributors of many brands of water testing equipment in Singapore but the following are the few I have worked with and feel comfortable enough to recommend.
  1. Most of the equipment comes from the brand, Aqualytic. Local distributor is Quantum Technologies Global Pte Ltd.
  2. The Hach series of products (including test strips) is also very good as it is a very established supplier in the area of water testing. Local distributor is Fluke South East Asia Pte Ltd.
  3. The YSI brand is also very reputable and their products are usually designed tough for field work. One distributor is Spectra-Teknik.
I am not sure about bksna as I have never used their equipment before or heard any reviews about them. Still, you can go ahead to check out their specs and prices and compare to the others above.

Good luck!