it is not a necessity, but it is well worth the $$$ for the headaches it
will save you with algae problems.

without it chances are great that your tank (especially a fish only) will
become infested with thick hair algae and it will cover everything in the
tank. ro/di (reverse osmosis/deionized) water helps reduce the chances of
this considerably due to it removes all the unwanted things from your tap
water that these nuisance algae's feed on.

hope to have helped
kc

"Veggie" wrote in message
ink.net...
I'm a newbie setting up a 55 gal fish only aquarium. I have been
planning to do a freshwater setup, but realized lately that the most
colorful and interesting fish IMO are sal****er. So, I've been looking
at sal****er instead. Still fish only, and flake eating fish only if
possible. Everything looks doable for a newbie like me, not too much
more than fresh... except reverse osmosis / distilled water.

Is that RO/distilled really necessary? That would add substantially
more $$$ for those that don't have a RO setup, like me.

Thanks in advance