Aquaguru

I was just wondering if it is ok to use the RO/DI water that I have been using for my saltwater tank for my new freshwater tank?

Peterpiper

Best thing you can use!
Is it a heavy planted tank?

griffin

it would be fine for top offs, but unless you're adding stuff (salts, minerals, etc) back into the water, it isn't necessarily the best stuff to do water changes with. hope that helps

sirdarksol

Okay, to fill out both previous answers, RO water is great, as long as you add something back into it. RO water lacks minerals that are normally in the fishes' cells. The result is that water will flood the cells and will potentially cause the cells to rupture.
There are additives specifically for freshwater tanks using RO. Drs Foster and Smith sell them, and I'm sure other places do, as well. These allow you to customize your water to precisely the pH/hardness you need.

pepetj

Reversed Osmosis is one process, De-Ionization another.

I don't feel DI is safe for freshwater, but RO is. However if you go for 100% RO water you must add trace minerals. I do use RO but after reading DI, discard its usefulness in freshwater tanks.

Keep your eyes on GH and KH. If KH reaches 2 DKH or less, your tank is at imminent risk of pH crash. Also a very low GH, say 3 dGH, could be hazardous to your fish health, due to the osmotic processes at cellular level (minerals would be drawn out of cells into the water).

Pepe
Santo Domingo

Aquaguru

So should I get rid of the DI part of the system. I think I can remove this part since it is a 4 chamber unit. I will have to check for sure. Can I get the additives at any LFS? It will become a planted tank. I am in the process of converting my SW to a FW. It is 120g

Peterpiper

So you dont use a "Mineral Block" in the system over there?
sirdarksol, You are correct,
But
IMO, it is far easier to check the redox potential, have the minerals there, and they will be used as required.

griffin

just out of curiosity, why do you want to use RO water? i would tend to think that using tap (dechlorinated) would be cheaper/easier than RO or DI

Aquaguru

I already have the RO/DI unit from having a saltwater tank which ro/di water is the best you can use for a sw tank.

pepetj

If you are going FW then I suggest you sample your source water. You might find you have pretty good water to begin with.


Test for ammonia, nitrites and nitrates. Keep in mind chloramines might produce false positives in some ammonia tests.

If your water if safe for nitrates -some have reported nitrates reading in their tap water, then measure GH and KH.

Take some shallow plates and put some water in them, let sit overnight; early morning measure for pH.

Using RO should make sense if you want to keep delicate soft-acidic species (e.g. Discus) and you might need to tamper your source water parameters. Mix and measure until you get your safe target area.

Any commercially available brand for trace minerals for freshwater use should help you keep your tank water stable. Again, a REDOX potential reading should suffice to let you know where you are standing.

An easy way of screening for REDOX is: take some water out of your tank with a disposable plastic cup. Add some Methylene Blue and if its dark color fades, even a bit, your tank is likely to be OK.

UV sterilization is another easy way of keeping healthy REDOX potential.

Pepe
Santo Domingo

musicman4567

To answer your question of where to get the additives, most large chain fish stores don't carry them (at least they don't around here). You can order them from drfostersmith.com or check a locally owned specialty shop. I know mine has them.

Aquaguru

alright sounds good thanks