So, I will start here. I have had a 55 gallon freshwater tank, for 3 years now. I have only used Tap water, on the initial fill, and all water changes. I know I know, Noob right?
Well after 3 years the tank has had zero serious algae blooms, i could probably go a month without cleaning it, i take great care of it though. im very happy with it and think its very stable.

I just purchased a 120gallon tank with all the essential equipment for a reef/fish tank, 4 power heads, skimmer, and biofilter.
my main question is would it be okay to cycle the tank by using only tap water at the start with about an 80%fill?
i plan on doing 25% waterchanges weekly, and Purchasing RO/DI mix for all the water changes, So no more tap water.. for the first 1-2 months i will only have live rock and live sand. unless i become extremely confident that its cycled well..

my question is since ive had success with my freshwater tank, thats littered with plants,and only using tap water, would this plan be okay?
i mean after the initial cycle is done it will be almost all RO/DI after all the water changes.. and when i test the tapwater for nitrates it comes up 0ppm.
i have read online on forums, but most people are biased either because their tap water is terrible, or they have never tried it..
will 3-4 weeks be long enough for my live rock and sand to absorb the unwanted/unfiltered water? or since my water is good, would it be bad for it at all..
i will be purchasing 350-450$ of live rock and sand this weekend.
Thanks..
Mike

This post was edited by xtraflac on Oct 17 2016 09:24pm

maybe you can try user named "skinned", think he has a salt water tank.

this forum is probably better, first topic is a guy building a big custom tank also
http://forums.d2jsp.org/forum.php?f=139

Hello,

I would avoid using just tap water right off the bat starting out your cycle. Your live rock/sand contains many beneficial bacteria when first starting. Tap water contains many harmful metals and chemicals that can kill life growing on your rocks. However if you cant get your hands on and RODI water or machine ( Aqualife sells a cheap RO buddie which isnt too bad), I do believe theres some "water purification" kits you can buy cheaply. In the end you could probably get away with it if you wait long enough doing many water changes, just make sure to check your params.

Good choice on a 120 gal you should be able to have quite a lot of fun with it. I regretted starting out with a 65 and being limited to the kinds of fish I could put in it.

What are your plans in terms of corals going in the tank?

Hope I helped somewhat.

(6 years experience with saltwater tanks)

After thoroughly looking into it I'm going to need to do this on a budget and slowly.. And that's most likely the best idea.. My plans now are to buy a digital refractomer and ro setup first, possibly buy 20 lbsand and 10pounds of Rock this weekend but I'm not sure how my funds are now that I'm going this route.. Might as well not fuck around..
My freshwater tank is awesome.. male/female yellow lab, 2 blue zebra males, albino red zebra male (that runs the tank)
But the messed up part is I have 5 plants on one side with a power head and 3 demasoni rule half the tank
Also have 5 clown loaches
Amazon swords and a 2 large leaf Anubis.

As for corals I'm not even sure yet , I like acroporo and soft long ones. I just stated so I don't know the ones I want unless I see them


This post was edited by xtraflac on Oct 18 2016 06:20pm

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