pH drop and low kh - How can I buffer my water? - The Planted Tank Forum
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post #1 of 3 (permalink) Old 09-27-2015, 09:48 AM Thread Starter
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pH drop and low kh - How can I buffer my water?

I've got an aqueon evolve 8, so ~6 gallons of water. Until tonight, everything has been holding pretty steady, gh of ~100 ppm and kh of ~40 ppm as per the API test strip. I've had a pH of ~7.6-7.8 for the entire month I've been fishless cycling.

Yesterday I tested the pH and it was nearer 7.4, using the API liquid test. I checked it this morning and it looks to be somewhere below seven. It's a bit hard for me to tell the colors apart, but I would put it at 6.6.

Ammonia etc is at 0/0/20 (I let it go for a bit to feed the plants; I don't plan on letting nitrates get very high when I have a fish.) I dose excel daily, .5 ml, and flourish 3x a week, also .5 ml.

The tank is planted, obviously, and I have one nerite snail in there, so I know their respiration can contribute to a pH drop if my buffering ability is low.

So, I guess, the question is... how do I buffer? If I use crushed coral, will that make my pH skyrocket? Will I need to add baking soda to my water/in with my water changes? I've read a lot of conflicting information about buffers being good/bad, so someone who's got experience with it would be great. I don't want to subject my fish to unstable pH.
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post #2 of 3 (permalink) Old 09-27-2015, 09:59 AM
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Don't know the exchange rate so I will talk about number of drops to get the color change.
A KH of three(drops to get that color change helps to stableize the PH.
Bakind soda needs to be added every water change or putting a teaspoon of crushed coral in like a piece of pantyhose in the filter will last much longer. Adjust the amount according to the Ph raise.
20 is a good nitrate level for a planted tank. Won't harm fish till over 40.

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post #3 of 3 (permalink) Old 09-27-2015, 10:39 AM
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From what I've read, one should pay attention to GH, KH, and TDS more than pH. GH and KH should be about equal. How much depends on the fish and plants you have. 40 ppm (about 2.5 dKH) seems very low. My tap water has a higher GH than KH level. I use to raise KH because I think potassium is better than sodium (using baking soda) in the aquarium.

The amount of CO2 in the water can affect the pH reading. Plants use CO2 when there is enough light for photosynthesis, but when there is no light, they have a net production of C02. So, depending on your KH level, pH can swing a considerable amount during a 24 hr. period.

Fish aren't that affected by pH changes that much. They are affected by rapid changes in TDS, GH, and KH. What has traditionally been called pH shock (when moving fish) is probably TDS shock.

Crushed coral is good, but slow and I wouldn't know how much to use. If there is something in the tank continually lowering KH by more than water changes can compensate for, then coral could be useful. If you just need to adjust the water added at water changes, potassium bicarbonate would be easier to deal with.

Last edited by Argus; 09-27-2015 at 10:42 AM. Reason:
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