I have two cherry shrimp 10 gallon tanks almost set up identical. Pool filter sand substrates, planted, drift wood, and sponge filters. I use RO water and remineralize with Equilibrium. One of my tanks pH has been slowly dropping and is now around a 6. I removed the drift wood thinking this was causing the drop. Vacuumed any debris from the substrate and it will not come back up. I do weekly water changes of about 25%. The pH will come up a little but in a few days drop back down. Thinking about completely removing the substrate and go bare bottom to see if I can get it to balance out. Not sure how I can have two similar tanks and one have a lower pH than the other. Any thoughts?

R/O water has nothing to buffer (bi/carbonates) in your water, so it doesn't take much to swing it either way. A bare bottom tank isn't going to make a difference here. With inert substrates, adding a little baking soda to water will raise pH/KH easily enough. You can also add it to your R/O holding tank too to get pH where you want it beforehand. Or just use a different remineralizer that has a KH booster in it such as Salty Shrimp KH/GH+.

+1 @madcrafted - you are adding GH to your RO water. KH is what helps to control pH and it doesn't sound like there's any KH in the water.

Just ordered some salty shrimp and will give that a try. Thanks!

Wow, i’m So glad I saw this post. My PH is dropping/has dropped to 6, as well. I must admit I do not understand the KH test. One drop changed the water in the test tube to a very pale green. It got a little darker green with each drop I added......all the way to 7 drops. Does the changing to extremely pale green with the first drop mean my KH was 1? This was my tap water. Guess I need to find some kh+. The ph out of my tap (well water) is 6.4, but I store up my change water and that water measured 7.something (can’t remember)——just know it was in the 7s. Nine Gal. Dennerele shrimp tank, heavily planted, catappa leaves, mineral rocks, spiderwood, Dennerele ‘soil’/substrate. All other water parameters are in normal range. TDS 250. My shrimp are reproducing, but i’m Still losing some adults and probably some babies.

The Dennerle shrimp soil is a buffering substrate, so you *DON'T* want to add KH to it!

@Lin, it sounds like you are talking about GH and if your GH is reading at 1 (or potentially 0), then that's an issue!

Directions for Testing KH

1. Fill a clean test tube with 5 ml of water to be tested (to the line on the tube).
2. Holding the bottle vertically, add KH Test Solution, 1 drop at a time. Be sure to count the number of drops being added.
3. Cap test tube & invert several times after each drop.
4. The test is completed when the water in the test tube, after having been shaken, turns from blue to yellow. If you have difficulty discerning the color after the first drop of test solution is added, remove the cap from the test tube and, while holding it over a white background, look down through the tube.
5. The KH value is determined by the number of drops of test solution that must be added to turn the water in the test tube bright yellow.

Directions for Testing GH

1. Fill a clean test tube with 5 ml of water to be tested (to the line on the tube).
2. Holding the bottle vertically, add GH Test Solution, 1 drop at a time. Be sure to count the number of drops being added.
3. Cap test tube & invert several times after each drop.
4. The test is completed when the water in the test tube, after having been shaken, turns from orange to green. If you have difficulty discerning the color after the first drop of test solution is added, remove the cap from the test tube and, while holding it over a white background, look down through the tube.
5. The GH value is determined by the number of drops of reagent that must be added to turn the water in the test tube green.

I do not understand the KH test. One drop changed the water in the test tube to a very pale green. It got a little darker green with each drop I added......all the way to 7 drops. Does the changing to extremely pale green with the first drop mean my KH was 1?

For the GH and KH test the shade of the color or how dark it is doesn't matter. As soon as you see a color change you stop adding drops.

KH goes from Blue to Yellow

GH is Orange to Green

You are only looking for the color change. If using KH and it goes from Blue to a greenish color, then the next drop should be yellow. You could say it's a 1/2 degree if it does that.


So make sure you have the right test because KH end color will never be green. It will be yellow. If it changes on the first drop to the color it's supposed to be, then the result is 0-1.


Here's a video if it helps to make it clearer.