RO water V Tap water?

  • We are currently upgrading MFK. thanks! -neo
I have heard that you should not use RO water on fresh water systems except for top off. The reason being that RO water is similar to distilled water and acts as a solvent (in a minor way) because it has no solubles in it. I have heard it is not very good for you to drink either. Salt water tanks have salts and minerals added to the water so in that case, it would be the best thing to use as it will dissolve the salt mix well and when topping off does not add anymore "stuff" to the tank. For top off, it should not matter salt or fresh water and I would think RO or distilled would be best.

I think it really depends on your tap water as to if it is OK to use strait (other than de-chlorinate) or filter by some means. I use tap water for all my tanks but I am on a community well and I know what I have at the tap.

Carbon filters do a good job of removing chlorine and several other toxins but leave most of the beneficial minerals. If you are only worried about chlorine, than you can leave the water out for 24 hours to let the chlorine gas off, this can be hard to do if you are doing large water changes, unless you have a large container and plan ahead. If the water is not pressurized, the chlorine should gas off or so I have read, I have never tested this myself, but I have used the practice for watering plants.
 
I've always used 100% RO with some bags of crushed coral in the sump and and in the holding vats to give it some ph stability/buffer. I have it set up to automatically change 10% of the water each day...it has worked flawlessly. No unwanted algae, crystal clear water, 6.5 PH all the time. Rays, discus, other fish are growing a thriving. I would never do it any other way. The risk of using someone else's source water (city or straight well), doesn't sit well with me. I have heard WAY to many stories on these forums of people coming home to all dead rays due to some unknown city "flush", "additive", or other issue from non RO water sources. I run 2 RO units 24/7. - 1 directly to the tank for the automatic water changes, and the other RO unit to large holding bins for emergency or planned water changes if necessary. (I also run the overflow line to the dog and cat water bowls..everyone is happy and healthy)
 
Not all tap water are the same. I would test the water for hardness before deciding which route to take. Well water is extremely hard and might not be as suitable for rays. Yes, using straight RO water all the time is not a good thing. Fish just like people need electrolytes in order to function properly. Cells communicate by minute electrical charges and PURE water does not conduct very well. This is why a person can die from drinking too much water.
 
If it got to the stage where only R\O water could be used for me it would be completely impractical...for 35 years plus i have used tap water on all my fish with good results.
 
Right now I use tap water. I am going to get an RO because I have heard more good things about using them than bad. As freshfishing said there are just to many possibilities of changes with regular tap water.
 
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