DIY Tap Water Filtration & pH Reduction

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Kinetix

Aquarium Advice Apprentice
Joined
Aug 12, 2005
Messages
17
Location
Montréal, Québec
My Toronto municipal tap water fluctuates between 7 and 8.6- so there are days when filling up the tank is an easy option, and there are days when it isn't.

Most of the time, it's on the alkaline side of 7. Since I had plastic plants in my 20G tropical, it's made sense to use Proper pH 6.5 buffer to bring it down... then I decided that plastic plants are ugly, and as you know, phosphate buffers and plants don't mix.

As a result, I've realized that it's pretty crucial that the water goes into the tank right from the start.

I looked at a few filtration setups sold at the hardware store. One thing that I realized that they all had in common was the main filtration was always activated carbon. I already have a filter in my home that uses activated carbon- the Brita.

This morning, I decided to experiment. I took a pH sample of the tap water- today 7. I filled a Brita pitcher using the same source, and took a reading. I was amazed that my pH had dropped to 6 (or lower- my test kit doesn't go any lower).

That means that using the right proportion of straight tap water to carbon filtered water, I can match my preferred pH of 6.5-7.

This whole thing does raise a few questions though:
-Why do tap water filter units cost at least $70 at the LFS?
-How come aquarium books tell us to use pH adjusters and buffers rather than just run tap water through a pipe filled with activated charcoal?
-How come the carbon filter pack in my filter doesn't have the same effect on my water?
-Does anyone else here filter their tap water using a homemade device?
 
I use a Carbon filter on my cold water line that I fill my tanks with. I have never seen that type of fluctuations in the pH, that you are reporting. I have found that the pH is a normally 7.4 to 7.6, and has been for years. My water comes from the same lake as yours, so TDS and such should be pretty much the same. Keep in mind that the chlorine in the water will raise the ph and removing it will lower it slightly. Lake Ontario water is a medium hard water, so it surprises me that you are getting an acid pH after dechlorinating (which is what the carbon fiter does). In answer to your second question, carbon should not do what you are accusing it of, which also answers the third question. And, for the 4th one, I use a canister filter of the type available at CTC or Home Depot, that uses a carbon filter that costs about $15.00 for 2, making it much cheaper than de-chlor. I don't pay any attention to the pH anymore, since the lake Ontario water seems to be ideal for a large variety of fis. I have bred Tangs and angels in the same water, so I have no interest in using buffers. I don't believ that pH is a factor with most fish (discus may be the exception). Getting back to the fluctuating pH, I wouldn't be concerned with that since the more important factor is the TDS and that is unlikely to change much from day to day. As far as $70.00 filters from the LFS, it is because everything costs more there.
 
Why do tap water filter units cost at least $70 at the LFS?

They do alot of stuff, is my guess. Most are 5 or 6 stage filters that give you nice clean RO/DI water. An AC filter is just one of those 5 or 6 stages.
How come aquarium books tell us to use pH adjusters and buffers rather than just run tap water through a pipe filled with activated charcoal?

Most aquarium books are paid by companies to feature thier product in their book. It's all a competition for advertisement. The fact of the matter is that you don't want to use pH buffers. If your pH comes out of the tap normally at 7, why do you want to change it? Are you trying to get it acidic for a reason?

The only reason that you got a different pH value with your brita filter is that (and this is just my slightly educated guess) it took alot of the hard minerals out of your water that can cause a more alkaline pH. How often does your pH flucuate? Are you testing it directly out of the tap? Let is sit overnight, and then test again in the morning to get a more accurate reading of your pH. :)
How come the carbon filter pack in my filter doesn't have the same effect on my water?

AC removes inorganic particles from the water by absorbing them. It's a small amount also, but using AC alone will not alter your pH. It's likely your brita filter is getting rid of that extra hard minerals that cause your pH to test alkaline.

What kind of fish are wanting to keep?

Does anyone else here filter their tap water using a homemade device?

I don't, and applaud you for having the talent to build one. lol.

Hope I helped a little.
 
The Brita type filters will slightly lower the pH but they will add salts to the water in the process, which you may not want in your tank. Regular aquarium charcoal does not do this. Charcoal can be made using a number of different materials, and aquarium charcoal is often made with bituminous coal and other things, where horticultural charcoal or water purification charcoal is made from wood, for instance. Brita filters use charcoal plus an "ion exchange resin" and that's where you get your sodium.

The adsorptive powers of charcoal are short-lived, and it needs to be swapped out very frequently to do you any good, so it is not a particularly cost-effective way to handle larger volume water treatment. Look into reverse osmosis purification for your tank, which can be mixed with your tap water to add the minerals necessary to sustain fishy life. This is what most people do when they have trouble with municipal tap water.
 
BillD, while I appreciate your response, it is often best not to tell someone with measurable, verifiable, and repeatable results that their results can't happen. My tap water pH fluctuates. That's a fact. We may get our water from the same lake, but there's a lot that happens to it between the time it's in the lake and the time it's in the tank. I did the test, the pH was immediately acidic. Don't ask me how, it just was. The test kit confirms it... although after letting the bucket sit and bubble through the day, it unfortunately does go back to the original pH value- so the water is buffered.

Devilish turtle, it's not the moderate pH days that are the problem. Days when the pH is 7 to 7.5 are few and far between. Most of the time, my tap supply is between 8 and 9. I'm not comfortable with that in the least.

It does look like I'm going to have to go the professional RO route.
 
The pH fluctuation you seem to be getting may well be due to differing amounts of CO2 in the water. CO2 makes water more acidic.
 
That doesn't seem likely given that it's a water filter. If an easy way to add CO2 for plants was to just add a pitcher full of Brita water, then planted tank enthusiasts would have been all over it a long time ago.
 
Kinetix said:
That doesn't seem likely given that it's a water filter. If an easy way to add CO2 for plants was to just add a pitcher full of Brita water, then planted tank enthusiasts would have been all over it a long time ago.

It is not the Brita filter adding CO2 - the CO2 is in the water in the pipes, and it outgasses after it is drawn from the tap. This is very common, so that is why people will test pH of their tap water after it has been sitting out overnight, so they can get an accurate comparison of tap water pH to tank pH. After sitting out the pH rises.
 
Kinetix, I was not disputing your test results. My point was that even though the pH results were different from your samples to mine, the source is the same so the TDS is more likely to be the same, so you can ignore the difference in pH. You are quite right in say ing that the process can alter the water, but unless the city is adding buffers the water (yours and mine) should still be similar, if not identical. There is good eveidence that so called pH shock is in fact caused by large differences in TDS not pH. While I have messed with pH and water parameters in the past, I try to avoid it as you can breed almost anything in Lake Ontario water, without altering it. I'm basically too lazy to do something that doesn't need to be done. Many people leave the hobby when it becomes work, and being lazy, I am always looking for the easiest, simplest way to do things. For that reason, I use carbon prefiltration, a gooseneck on my filler, and all my tanks are near the floor drain. I also don't like to spend more than is necessary; my motto is cheap is good. Hopefully, that will explain where I'm coming from, and my response.
 
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