[cosmo76]

Hey guys,

I'm reading very conflicting info on this. I got my son a 5g tank to take care of, so he'd leave my 125g reef tank alone. Everything was running well until a small crash happened. I started using RODI water about the time of the crash, so logic says that was the cause, but common sense to me doesn't understand why!

Its a 5g with small basic fish like tetras, danios and a few basic 101 plants. But some of the plants died suddenly and disintegrated quickly, and now all the tetras died in about 2 days, but the rest of the fish seem happy as heck.

Personally, I'd rather not start having to dose a little freshwater, so should I just switch to tap again and treat it?

TIA

 

[Flint]

RO water does not have the nutrients and minerals that tap water does. It is too pure for freshwater fish, they need certain things in their water to be happy, not to mention it may have caused an unstable pH (where it doesn't in saltwater tanks due to substrates and live rock) because unless you have crushed coral substrate, there was no buffer. The plants also need the nutrients and minerals that come in the tap water unless you are dosing it with other additives. When using RO in fresh water you MUST add some stuff back before putting it in the tank. So to answer your question, yes, you need to go back to using water from your tap.