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Reverse Osmosis water


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I just got a reverse osmosis & Deionized system it is a 6 stage system that does 100 to 150 gpd depending on water pressure.  I am curious how everyone that has these systems uses them in their aquariums.  Do you mix it with normal tap water or do 100% RODI water.  I don't like that it has so much waste water which really sucks so has anyone still used that for the tank or anything?  Also I have really hard water living in the Rocky Mountain area.  My Ph from the tap is somewhere between 8.4-8 and when I have been mixing different ratios in my api test tube (1/4 tap,3/4 rodi, 1/2 tap 1/2 rodi, 1/2 tap, 2/3 ro)  I see my ph go down to maybe 7.4 not really knowing much about water It doesn't feel like a big drop.  When I do 100% rodi water it is either 6.0 or lower.    Anyone seen or know of any huge benefits with how this effects freshwater tanks in the long run? Thanks for helping me keep my fishbros happy!


Here is a link to the RODI system I have 



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The PH scale is exponential, so the drop from 8.4 to 7.4 is actually massive. 6.0 is neutral, and I would honestly not enjoy working with that water, so I would never use just straight RODI in a tank. I might use it for hatching killifish eggs in the future, but that's about the only time I would ever use pure RODI. I do use a mix, but that's because my water tests off the charts in KH/GH/PH after oxygenating in the tank for a while.

I do use RODI for top-offs in my only tank that evaporates. But I try not to go to far with that, because the mineral content is not static. I want to replace whatever is lost.

So I guess what I'm saying is, there are benefits, but you probably don't need to take it very far. Most fish will live a long time in 8.0. 7.8 is great. 7.4 is great. Definitely don't use straight RODI. 

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