Ok, what's the skinny on RO/DI water

[Spoon]

My local aquarium guy (and good friend) has me using RO water to keep the phosphates out of my tank. (At least I think that's why) I had a hair algae problem in my original 20 gal tank and it's been fine since I updgraded to a 45 gal.

But, I was just told in another post that straight RO water is not good for fish. Should I be adding something else to it?

Are there any sources for complete information on the topic?

Thanks

 

[Allivymar]

RO pulls ALL the nutrients out of the water; it also removes some of the beneficial trace elements. There may be a need for a buffer as well, but I can't quite explain it cause I don't use RO water and don't totally understand it LOL You might want to try the RO faq over at WetWebMedia:

http://www.wetwebmedia.com/rofaq2.htm

 

[shawmutt]

look for a bottle of R/O right, it will put the nutrients back into the water. You can adjust the water for the type of fish you have.

 

[Spy_90]

or just mix RO with your tap water? that's what i do. i end up doing about a 50/50 mix to get PH/KH/GH all right.

 

[RogerMcAllen]

Pure RO would make the fish blow up, kinda. Osmotic pressure is something that exists everywhere two liquids of different concentrations are separated by a semi-permiable barrier. Whichever side has a higher concentration of particles, is the side the water wants to go to. RO works by putting pressure on the high concentration side forcing water to "reverse" and create pure water. This is why FW fish can't live in SW. The insides of the FW have a low concentration, so the SW will suck a lot of the water out of the fish and it will die. This is the same reason drinking SW makes you get very dehyrated. On the other end, if a fish is put next to water that has no concentration, that water will start absorbing into the fish causing the cells to burst and the fish will die. This would only occur if you were to put the fish directly into the RO, so don't worry too much.

 

[TheNewGuy]

another product to look at is equalibrium. it comes highly recomended by a few different sites I have read.

 

[Jack]

Roger, excellent explanation but I don't subscribe to your "blow-up" theory. There is a greater concentration of salt in the FW fishes body, whether the water is just "fresh" or whether it is RO. Hence, water will be absorbed into the body either way. For this reason, FW fish drink very little water and SW fish drink a lot (according to my highschool biology teacher).

If you use RO/DI, some nutrients will leach into the water from gravel, food, and such. RO water really shouldn't hurt the fish as plenty of nutritition is taken from food. Plants of course need the additional nutrients. If fish need a high or low pH, you could have some problems as RO/DI water lacks the buffers present in tapwater. As others mentioned, they sell chemicals to deal with this sort of thing.

If one is not interested in keeping a tank with plants, RO/DI can be a good option. With less nutrients, you should have less algae problems provided the tank is not overstocked and you don't overfeed.

 

[RogerMcAllen]

The fish doesn't blow up, the cells expand and burst in the sensative tissues such as the gills.

 

[fishfreek]

Take a look at this

http://www.aquariumadvice.com/showquestion.php?faq=2&fldAuto=25

A member of ours was involved in a simular debate many months ago so she took it upon herself to contact many sources and get feedback. All their feedback is posted in that article.

 

[RogerMcAllen]

Thanks for the info.