african cichlids and water hardness

Subject: african cichlids and water hardness Sun Apr 06, 2008 11:47 am

Played chemist with my kids last night and did water analysis on 4 tanks and the tap water.
We found the cichlid tank is now pH 7.6 , dH 6.7 , no measurable N anything at all. This is the softest it has ever been. I need some corrective hardness without dumping baking soda in it. I'm thinking rejuvinate the gravel with a new 5# crushed coral mixed into the substrate.

There are no live plants in this tank except algae. One of the veggie foods I fed them was heavy on the Spirolina and thus 'bout half the algae is now that one.
The water company got their hardness to dH 5 , pH 7.7 (this week).

I'm thinking the crushed coral in the gravel is getting exausted as to what is being disolve into the water thru the under-gravel filter. The bluestone rockwork might have reached a steady state too, since the water has been much harder for the past two years with only fish excrement for acidity.

SO my protocal, without shocking/stressing, becomes what? Change water, change filter media, add crushed coral mixed with substrate. Retest hardness a lot? Do these numbers make any sense in the first place?