My tap water comes out super hard at around 15 or 16 GH & KH. This is fine for my 60 gallon species only Brichardi tank. However, I wanted more of a planted tank with softer water that fish like Neons and Rummynose Tetras would find more hospitable. For this reason I bought an inexpensive RODI unit to use on a new 29 gallon. At first, I was mixing half RODI and half tap to provide the necessary minerals but the high silicates in the tap water gave me a dose of diatoms and the resulting “brown algae”. The half tap half RO provided a GH & KH of closer to 7 and ph 7.8.
For water changes on that tank, I’m now using straight RODI water wit Seachem Equilibrium and Alkaline & Acid Buffers to get to this same parameter.
Is it really worth it, is the question. Well, I ask myself the same question when I’m lugging 5 gallon buckets of RODI water from the hall bathroom to the living room. I think I have a pump that will fit my Python hose so I can refill from the buckets that I store and treat the RO. Which reminds me...the RO water has to be heated as well; which is my latest challenge.