Originally Posted by Desert Pupfish
So if a high CEC substrate like STS lowers the pH (and presumably the KH as well) of hard water, how long does this effect last? Presumably you'd get an initial big drop while cycling the tank, but then what? Once the STS has reached saturation with calcium ions, does the pH & hardness then go back to whatever those levels are in the water you use? And how long does that take?
I'm starting a new tank with an organic peat potting soil covered with STS, and what to know what to expect. Don't want to be stressing my fish or plants with drastic swings, nor do I want to invest in fish or plants that prefer low pH/low hardness if it's just going to eventually go back up the high pH & hardness of my tap water. (I know I could use RO, but I'm trying to keep things simple & cheap)
Really from what your describing you need to slightly rethink your approach. Use probably 1/3-1/2 as much organic/humic layer as your envisioning in your head and use a CEC layer with a much lower potential than your envisioning. Most setups like your envisioning perform great (spectacular actually) when first setup but once reality sets in and top layer of substrate build up some mulm things quickly nose dive about 6 months in.
If you want to give me dimensions of your gravel bed, lighting estimate, plants you want to keep, and co2 situation and I’ll try to formulate a more long term reliable solution for you.
I prefer setting up a tank so it may under perform at 1st but at max of 3-6mo in it will start excelling and be as low maintenance as possible.
Last edited by DaveKS; 05-08-2019 at 08:24 AM.