WATER SOFTNERS AND DI UNITS

[dave Cox]

I have well water and a water softner. The water out of the tap has a pH of 6.8 and KH of 4. After a day the pH climbs to 7.8. I'm getting some alge growth along with the pH swing so I know that I need to take a closer look at my water chemistry. I'm going to start using a tap water DI unit for the short term. If it's good for 150 gallons that only 12 cents a gallon. I don't intend to bread Discus any time soon and they don't seem to be bothered by the current water conditions. I do want to take a methodical approach to improving the water. I would like to do it without an RO unit if possible. My water softner already puts a lot of water down the drain and it looks like an RO unit puts a couple of gallons down the drain for every gallon it makes. I would also probably have to buy a booster pump to get the inlet pressure up for the RO unit.
I assume the water softner is putting sodium in the water as the result of ion exchange. What should I be testing for in the water I'm putting in the tank? Should I use the harder water going into the water softner instead of the softer water out?
Any ideas?

Thanks,
Dave