[snafuspyramid]

I put two tablespoons of shell grit into a 20 gallon back when it had sailfin mollies in it. It's evenly distributed throughout the substrate.

Recently, we pulled down the tank and replaced the mollies with a breeding pair of rams and a few minnows. We didn't change the substrate though.

Tap water here has very low kH, 1-2deg and usually sits about 6.5 after a week or two, which is about right for this tank. I've also got a lot of driftwood in there to acidify it a bit.

But, the tank keeps bumping up to about 7.6. Is there any way to counteract this without just replacing the substrate?

It's my girlfriend's tank. She doesn't want to change the gravel (understandably) while I think it can't be avoided.

Kindly adjudicate :biggrin:

 

[bsmith]

I dont think so.

 

[wkndracer]

Readings will rebound I think if you try chemicals to shift it.
7.6pH isn't too much more than a neutral reading, I would guess around 3-4dKH and until the mineral supply is exhausted it will continue to rebound. Perfect example of why I recommend not doing the shell or shaved cuttle bone addition setting up dirt tanks. Received some flack over my position from several folks on the forum but once it's added control is lost.

won't last forever though