Crushed coral for my discus tank?

Question
Hi Karen. I am setting up a 75 gallon discus tank and am
considering using crushed coral (or a "cichlid" mix of coral and
gravel). Have you known anyone that has tried this? Do you
know if the coral contributes to more acidic or alkaline
conditions? Our well water is extremely soft, however the pH is
slightly high, around 7.8 and I'd like to keep it around 6.8 to
7.0. Thanks for any help you can offer.

Answer
Dear Lisa, I'm sorry it took so long to respond, it's been VERY busy around here.

~Unfortunately I've never know any aquarist using crushed coral in discus aquariums. Crushed coral will certainly keep your pH and hardness high, but probably too high for the Discus who prefer softer water. Luckily most farm-bred discus are well adapted to harder water conditions and can thrive in them. But for spawning purposes, typically soft water is required. Adjusting pH and hardness is a very dangerous thing. Sometimes it works, sometimes not. More often the latter and the result of adding pH reducing powders and chemicals can cause very bad pH swings in your aquarium water and some very stressed Discus--or worse.
Probably the most important thing to know is your KH or Alkalinity level. If you have sufficient alkalinity, I might leave your current water parameters just as they are. But if you have low buffering capacity it is vital to add chemicals (which I would not recommend otherwise) in order to prevent a dangerous situation of pH drops and unstability, especially for the senstive nature of discus.

*Should you have a very low KH level (most fish are comfortable at a KH of 4-8) then you may try adding biocarbonate of soda to your water, or you COULD try the crushed coral...which should help but only use it in small amounts and it would be best for you to experiment with a not-so-expensive fish like Neons in the aquarium before adding your discus.

However,if your KH levels are too high (really not much of a problem as long as pH stays below 8.0ppm you can filter your water through peat, or dilute it with Reverse Osmosis water (R/O) before use.

Some experimenting and careful trails and hopefully no errors are your best bet at getting your water where it should be.  Could I please know your KH level? that would really help

A 75gal Discus aquarium is a wonderful idea and will surely be a very beautiful aquarium.

Best wishes and best of luck!
Karen~