Constant KH/pH Drop in New Setup
Sorry if this has been encountered before, but the search kicks out "KH" and "pH" as too common, and won't pull anything decent for me....
I recently started a 15H, and cannot, no matter what, keep the pH up. No matter what I do, the pH constantly drops, and the KH is being used up at a rate of about 10ppm per day. Any ideas? I'm hoping someone with a good chemistry background will have an explanation, but I can't figure it out. Tank details below....
Substrate: inert gravel with a laterite underlayer
Lighting: 2 x 36W AH Supply fixture
Flora: rotala wallichii, rotala indica, green cabomba, crypt wendtii, dwarf hairgrass
Fauna: 4 tiny Cherry Barbs, and about 12 MTS
Ferts: Flourish Excel, Flourish Potassium, Flourish Trace
Currently pH is being kept at 6.6 and KH at 60ppm (3.4deg) by addition of about 1/4 tsp of baking soda every evening. Can't keep this up forever, doesn't seem healthy.....
Some final questions/thoughts: Are my plants processing carbonate due to lack of available carbon, and chewing through my KH that way? Whenever I add baking soda, I notice a reddish build-up in my filter floss over the next day. Is some insoluble iron/carbonate compound forming? Or is this all just a fairly normal part of the initial cycle that will pass, and I'm freaking out for nothing??