Ro/di
- Thread starter Whiskers
- Start date
i will be using it for drinking water and possibily for one of my new tank setups. the fish i have now are used to the water i've been using and i don't want to stress them with overly purified water so i will keep them in the water that they are used to. i've been told that the DI part removes to many trace minerals from the water that are good for the fish. Is that true? i've read that some use the DI part as well for their tanks but i'm not sure if they have to add minerals to keep the levels up. I don't want to have to add a bunch of stuff to the tank when i can just use the RO side which won't remove all of the trace minerals but will give me a cleaner water quality. so i'm looking for some answers as to the water quality that come out of a RO unit like, hardness, what does it do to ph, does it lower the buffering ability of the water etc... before i screw anything up that i will wish i hadn't done.
You definitely don't want DI for drinking water. It doesn't taste good.
RO will basically remove all of the trace minerals from the water. What you can do is mix RO water with tapwater for your freshwater fish. That way, you get some of the minerals without having to re-add expensive additives. Pure RO water will have a hardness and KH of zero. Basically, there is no buffer.
I'd also add that drinking a lot of RO water probably isn't that healthy. We, too, rely on water for some of our calcium and other minerals.
RO will basically remove all of the trace minerals from the water. What you can do is mix RO water with tapwater for your freshwater fish. That way, you get some of the minerals without having to re-add expensive additives. Pure RO water will have a hardness and KH of zero. Basically, there is no buffer.
I'd also add that drinking a lot of RO water probably isn't that healthy. We, too, rely on water for some of our calcium and other minerals.
OK, so first off DI is not rated for potable water, bacteria *can* grow on the resin. So yes you want to tap off the line before it for your drinking water and lead that to your pressure/storage tank and valve. You'll also need a check valve (pressure rated and made for RO systems) after the Tee and before the DI stage.
As to using the water for your tanks. I wouldn't use either RO or DI or RO/DI as your sole source if at all... Unless it's going to be for SW. The main advantage to using it is being able to make your water from "scratch" so to speak. So yes you need to add some minerals back to the water, how much depends on what you are (or plan to) keep. Using "pure" water is just asking for problems
. It has absolutely no buffering capacity, so little in fact that even just atmospheric CO2 can drop the pH SUBSTANTIALY. Last time I calibrated my pH probe the DI water I was using for the rinse read around 5.5 (or in that neighborhood anyway... didn't pay that close attention lol).
Basically if you are keeping some of the more basic fish (or even some more advanced fish) it's much easier just to use tap water if you can. On the other hand if you want to breed some of the more difficult species (tetras, discus, some rare gourami's) or keep sensative wild caught fish, it *may* be worth looking into furthur.
Now, one thing RO/DI is AWESOME for right out of the unit is Evap top up. Because there is no minerals in it, you aren't concentrating the disolved solids when you add tap water. But how much that even matters is open to debate and IMO the answer varies from application to application.
Hope that helps even a little.
Chris
As to using the water for your tanks. I wouldn't use either RO or DI or RO/DI as your sole source if at all... Unless it's going to be for SW. The main advantage to using it is being able to make your water from "scratch" so to speak. So yes you need to add some minerals back to the water, how much depends on what you are (or plan to) keep. Using "pure" water is just asking for problems
. It has absolutely no buffering capacity, so little in fact that even just atmospheric CO2 can drop the pH SUBSTANTIALY. Last time I calibrated my pH probe the DI water I was using for the rinse read around 5.5 (or in that neighborhood anyway... didn't pay that close attention lol). Basically if you are keeping some of the more basic fish (or even some more advanced fish) it's much easier just to use tap water if you can. On the other hand if you want to breed some of the more difficult species (tetras, discus, some rare gourami's) or keep sensative wild caught fish, it *may* be worth looking into furthur.
Now, one thing RO/DI is AWESOME for right out of the unit is Evap top up. Because there is no minerals in it, you aren't concentrating the disolved solids when you add tap water. But how much that even matters is open to debate and IMO the answer varies from application to application.
Hope that helps even a little.
Chris
thanks lotus. now that brings me to another question to see if i'm wasting my time with the RO unit. if i add some of my tap water to the RO water, will the RO water take on my tap water qualitys or will the RO water change my tap water? in my tap water i have a high buffering, ph of 8.0 to 8.4, and a fair amount of hardness which i believe (been a while since i tested it) is apx 24gh. I don't have the experience with a RO unit to know which way this will work. i know i don't want ph swings but was hoping to get a lower ph with RO water for a fw tank. i've heard some use RO water for sw tanks but i think my normal tap water is ok for that. my one concern is that (the last time i tested a while ago) my tap water has a nitrate level of 40ppm but in my tanks its around 20ppm. i was also hoping that the RO unit will drop that level of nitrate so maybe i could eliminate some of it before it got to the tank. i'm most grateful for more answers.