Well water, water softener & fish deaths
We've had a planted tank for three years.
40 gallon breeder tank
Lights: 2x 39 T5HO 7hr/day
CO2: pressurized CO2, gla atomic inline diffuser, on 2 hr before the lights & off 1 hr before the lights go off, drop checker
Filter: Eheim 2217 and 2 powerheards
Fertilizer: EI dosing 50% water changes per week, flourish excel 10ml/day
Heater: hydor inline heater 78 degrees
We are using well water that has been run through a water softener that uses salt and some kind of iron removing chemical. We cannot use our untreated well water as it is so full of iron and other metals that is dark orange out of the tap. Even after going through the water softener, the water still tastes a bit metallic and and occasionally like sulfur (we drink from a britta filter). I've read that water softeners add salt to the water which is bad for the plants. I've also read that very soft water is bad for fish because it lacks buffers and therefore is subject to pH swings.
We have successfully grown many varieties of stem plants, java ferns, hair grass, anubias, lotus, hygrophila, and crypts.
However, we have been less successful with our fish. We have gone through a lot of fish over the last few years, none died immediately, or in large bunches, but there is constant attrition. We've lost: neon tetras, long fin white cloud minnows, fancy guppies, ottos, black neon tetras, glass catfish, panda corys, shrimp, and snails. Our most successful tank survivors are black neons, corys, ottos and a large bristlenose Pleco.
We do regular water changes and don't over-feed. We've never had any obvious disease outbreaks. We monitor our CO2 with a drop checker--aiming for lime green. The guy at our LFS thinks inconsistencies in our well water are to blame. This makes sense, given that the taste is not consistent. He says people around here get nitrate or nitrite spikes, which are bad.
If the well water is the problem, the only thing I can think of to truly address this is to get an RO system. I'm not opposed to this since we would be able to use it for drinking also.
But perhaps this is over-kill & we just need to adjust the gh and kh? We haven't tested these things in a couple years but last time we checked the Kh was 1 and the ppm kh/gh was 18. (we have ordered new test kits and will post the current gh and kh once they get here).
We are also struggling to truly "dial-in" our CO2. It seems like the fish are touchy and act sick whenever we adjust it. I've added an airstone at night to see if that helps. Perhaps having more buffer would make a difference. We are constantly struggling with BBA and would really like to get the CO2 up a bit without stressing the fish. I just started turning the CO2 on 2 hrs before the lights in an attempt to achieve lime green on the drop checker for as much of the lighted hours as possible.
So, bottom line:
Do we start from scratch with RO water, or do we try to work with the well/water softener water?
Will changing our water parameters help with keeping fish and shrimp alive and allow us to maximize our CO2 without stressing our fish?
What do you cleaver people suggest?
EDIT: A few pics...