Help regulating pH, KH, & GH

[LabTest57]

You can do a 16.6% water change everyday with RO water (pH at 7.0), if your kH is at at least 7 and pH at 8.2. However, in your case, your kH will drop -1 to -1.5 every 16% water change with RO water, and pH should drop temporarily -0.2 degrees until your reach about 6 degrees kH to notice some stabe results. Then, your pH should start moving downwards with more stability. If your kH drops too much (i.e. below 2 kH), you will notice instability again.

so whats about 16.6% of 29 gallons, it's about 4.5 gallons.

You should do a 4.5 gallon water change using RO water everyday until you get to your target pH and/or kH. Afterwards, mix some RO water with your source water to get the right combination of kH and pH in order to buffer your tank, so its' kH won't drop any furthur and pH would not fluctuate as much.


Instead of using well water, you can buffer the RO water with seachem alkaline buffers. Hope this helps a bit. =)

[LabTest57]

Forgot to metnion one thing. Having proper gH levels is required for pH stability as well. Keeping gH at least 1 or 2 degrees higher than kH is a must. Target gH should be in the 4 to 8 degree range for your type of fish.

[pamdaly]

I just tested 4 different proportions of well water with RO water. The tests came out like this:

For 1 gal well water with 1/2 gal RO:
pH 7.6
KH 14
GH 7-8

For 1 gal well with 1 gal RO:
pH 7.6
KH 9
GH 6-7

For 1 gal well with 1 and 1/2 gal RO
pH 7.6
KH 7
GH 4-5

For 1 gal well with 2 gal RO
pH 7.6
KH 5-6
GH 4-5

Questions:
1. Why didn't the pH go down as the KH decreased? Does the water have to sit for awhile?
2. You said it was important to keep the GH 1 to 2 degrees "higher" than the KH. It is always lower.
3. Am I correct in concluding that the eventual proportion of well to RO water in my tank should be 1:2? Does this provide enough minerals without adding Equilibrium?
4. If my KH is 5-6, why would I need an alkaline buffer?

You have been most kind in giving your time to my problem.

[LabTest57]

Your GH will be lower because it starts initially lower. If you want your pH lower, use use less well water. Instead of 1 gal for each test, use 1/2 gal. You should notice a difference.

I'm not going by the books in my calculations, I'm just making pure assumptions from intermediate math formulas. If your intial pH is 8.2, you would want to get down one pH level or to 7.2 easy by adding 3 gallons of RO water. A 1:1 ratio should equal to a pH of 7.6. A 1:2 ratio should equal a pH of 7.3, and a 1:3 ratio should have a pH of 7.15.

In your experiment, a 1:2 ratio should yield a pH of 7.3, but as you try to get closer 7.0 it's harder because RO water doesn't have any buffers that target a 7.0 pH (a pKa for 7.0). The broader the range of pH levels of two different solutions, the more fluctuation you will get; however, when it comes down to getting as close as you can to the target pH, the harder it will be based on other water parameters,etc.

I can google this for you, if you want a clear understanding and reference to what I'm talking about. =)

[Tech Support DD]

To answer your first set of questions, pamdaly:

1. Mixing your well water and the RO water should most likely help to bring your pH down.
2. Yes; it should bring it down safely (many people use this strategy with success).
3. With this new water source system you are using, you may or may not need to add Equilibrium. It will depend on what your resulting GH will be and the GH requirements of your fish and plants. If you are in the correct GH range after the fact, you would not need to use Equilibrium.
4. You may or may not need to use Acid Buffer while using RO water in your weekly water changes. It is difficult to determine what your resulting pH will be. You can certainly add Acid Buffer if you find that using RO water in your weekly water changes is not bringing your pH low enough.
5. We recommend using one or the other; you do not want to over do it with the pH lowering effects of both.

And to answer your second set of questions:

1. It may take some time for the pH to decrease. Your KH obviously decreased faster, but the pH may soon follow.
2. Plant preferences for GH will vary, but a general guide is about 1–2 meq/L (3–6 dH) or to match the existing or target carbonate hardness (KH), which, ideally, is also about 1–2 meq/L (3–6 dKH).
3. The ratio of well water to RO water may need to be tweaked (and will depend upon what you will be able to obtain). Again, whether or not you will need to add Equilibrium will depend upon the resulting GH of the replacement water (and, ultimately, the resulting GH of your tank water).
4. If your KH is 5-6, you would not need to add Alkaline Buffer.

We hope this helps :-)

[pamdaly]

Dear Tech DD,

Thank you for your response. It was very clear and I think I will go ahead and just use the RO in weekly water changes. However, I'd appreciate your thoughts on the following:

1. How urgent is it to get my pH (and KH of 13) down? I have been told that my fish will not thrive in the current levels. I also know it is stressful to change the water too often or in too great amounts and I could end up with ammonia problems. So, if possible, could you give me a ballpark range of time within which I should strive to get the pH down --say, 6 months?

2. It is clear to me from my test mixtures of well and RO water that the pH does not come down near as quickly as the KH. Could you give me an estimate of how long I should wait for the pH to come down before I conclude that I need to add acid buffer. For example, if I'm adding 4 gallons of RO as replacement water to my tank each week for a month and still see no decrease in pH, should I start adding the acid buffer? I may be being too obsessive about this but it's because I'm very concerned not to get some pH bounce that could hurt the fish. Let me know if I should ease up on this worry.

Again, I greatly appreciate your sharing your expertise.

[LabTest57]

Like Tech support DD said, you should tweak your well water to RO water ratio.

Look at it like this: It's harder to change your pH than your kH, so why not use more RO water than well water. Find a ratio that allows the kH to go up to 3 to 6 dkH (preferrably 3), so that the pH can stay on low side (i.e. it will be probably in the 7.2 to 7.6 range). The problem here is that the RO water isn't buffered, so adding well water will significantly change the pH upwards. 1 gallon of RO water + 1/2 gallon of well water (dkH 13) should give you about 6.4 dkH. 1 gallon of RO water + 1/4 gallon well water (dkH 13) should give you about 3.2 dkH.

[pamdaly]

I've just read about "Neutral Regulator" as described on this site under Products. It sounds magical, and too good to be true for my situation...especially since no one has mentioned it. Would this work with my well water and eliminate the need for RO?

[LabTest57]

Well, if your plants can tolerate a lot of phosphate and not wilt and have their leaves turn black, or if excessive algae doesn't starve your plants, then yes you can add it.

Basically, you can do this at your own risk. I've done it before, but it only works if you manually set the pH close to 7.0 to 7.2 and then add Neutral Regulator. After a few weeks, algae should appear and it will take forever to naturally get rid of it.


This product works best for non-planted aquariums...

[pamdaly]

Thanks LabTest57. I have a pretty heavily planted tank so I guess I won't be using it.