Ro/di Water?

[fish_tank0311]

Hi all.

I am now getting into my marine tanks (dont worry im keeping my gazillion freshwater tanks. Well i dont have that many, but i have 3 or 4 or 5 or 6 tanks, depending on what im doing. i have 3 normal display tanks, but now my angels are breeding, they have already layed eggs, my guppies already gave birth but the fry disappeared and same with my mollies.) Ok now enough of that. So i bought- oh 1 more thing before i start you can see my marine journal if you go into my profile and then see all my threads or whatever. Ok now i bought my RO/DI filter for my marine tank (reverse osmosis de-ionizing or something) because it is essential for them because the evapouration of the water will eventually make all the salts and small amounts of poisons in the water accumulate, eventually making a cyst pool. Now that made me think, do i need RO/DI water in freshwater tanks??? Im sure i get some evapouration but do i need it for freshwater?

 

[chrisbassist]

Have you successfully kept all your FW tanks without it?

So no, not needed.

 

[fish_tank0311]

Well yes i have but still. I have also successfully kept fish in plain old water without bacteria in it, that hadnt been cycled at all (as i didnt have a choice when i first got my fish) and they lived and turned out now 2 of my first 8 fish (4 being blue gouramis and 4 being angels) are now breeding, but are you going to tell me that fish dont need to be in cycled water too?

 

[robryb]

Using RO water for tropical freshwater tanks is tricky, you need to carefully monitor the PH, general hardness and carbonate hardness. You should generally do this anyway, no matter what your water source is, but it's not essential.

You need to remineralise RO water before adding it to your tank, and you can end up with the situation you're talking about with salts accumulating. This is why you need to monitor it, so if you see the salts are building up/ph increasing, you can ease up on the remineralising. If you see the hardness or ph are dropping, you can increase the remineralising. So by using RO water you can control what's happening with your tanks chemistry, but it adds an element of complexity which you may or may not enjoy.

 

[chrisbassist]

I too successfully kept my fist fish without a filter. It was a goldfish. It lived a lot longer than anyone else thought it would. It lived 5 or 6 years. You know, quarter of it's lifespan.

The point is, you don't need to do it. It adds time, expense and extra effort at every water change. You will need to mix with regular tap water to get some minerals in there, which also means you need to get the right amount of each or you risk having ph fluctuations.

Basically, it won't give much benefit, unless you want a much lower ph than you are getting out the tap,

but it leaves lots of other stuff wide open to mistakes which could kill everything.