The use of RO/DI water in a freshwater aquarium ...

Since the addition of my marine FOWLR aquarium, I have been making weekly runs to a new saltwater only LFS here in the area for my buckets of RO/DI water. Well since this got tiring rather quickly, I shopped around and got a great deal on an Kent Marine 60gpd RO/DI unit.

I would like to also begin using RO/DI water in my freshwater tanks as well but am concerned about the plant life and if water that pure lacks the nutrients to sustain plants. I do add plant food liquid once a week to the tank.

Interested in opinions on the subject ...

If you use just RO/DI water you would eventually deplete the nutrients and more importantly the buffering capacity of the water (rather quickly). Most people tend to either a) add a portion of well water to the RO/DI water to bring the hardness up to target level, or b) add a buffering agent. In either case you would still need to add some fertilizer unless your plant density is low or their requirements are low.

I personally use method a). It's been suggested that the plants do not require these steps. While I believe that's true, I've found that my plants grow much better in the RO adjusted water, it's also easier to manage

If you use ro/di water for freshwater, you need to add something like seachem equilibrium to restore the mineral balance and increase the hardness and then you will need to add some baking soda to increase the alkalinity to the level you desire. Without the bicarbonate your plants will die and the water will become too acidic.

Check this site out for good info!!

I tested the water last night and it was 6.0 and had little or no buffering capacity. The hardness levels seemed to be at normal levels (using those 5 in1 test strips). I added bicarb and the pH and alk were much better.

You can use Kent Marine RO Right.

that stuff is crap. I would avoid it at all costs. It adds far too many tds into the water for the minor increase in gh that it adds. And it also increases the ph, even though kent sayss it won't. Seachems equilibrium is a 1000% better. Especially for a planted tank since equilibrium has a good variety of the minerals that plants need for nutrients.