Using tap water?

rock_lobster · Mar 4, 2018

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andrewkw · Mar 4, 2018

What's in your tap water?

dansreef · Mar 4, 2018

In my opinion.....No. Buy yourself distilled water at the very least. Or.... go to your LFS and simply buy a container... and have them fill it up with RODI water. You can get a 5 gal jug that could last you a while. Do you want to run the risk of containments in your tap water getting into your tank? Is your tap water city? Is it well? Have you ever done a test of the water? There are reasons why most people filter their tap water for drinking, ice and cooking. The minimum standards of city water are still pretty lousy. If you have well water, heavy metals and other containments can be present.

I have a couple of local friends who have small tanks that come to me and get RODI. They will bring me beer every once in a while... Find yourself a local reefer who runs RODI. If there was an emergency... use distilled... infinitely better than tap.

Randy Holmes-Farley · Mar 4, 2018

There will be evaporation (must be) if you have adequate aeration. All of the air you pump in will become saturated with water and it evaporates away in that way. That said, you may have reduced evaporation but inadequate aeration and I'd be worried about that aspect.

The main problem is copper, IMO.

In a small tank with little evaporation, if you don't want to buy an RO/DI, then get it from an LFS or buy purified water from a store. Distilled, for example. The cost will be minimal if evaporation is as low as you suggest.

Greenfishman · Mar 4, 2018

Our water here is horrendous.....seriously it's a kettle killer. The best thing I ever bought was an RO unit for my tank, but I appreciate that everyone's water is different and have heard of people keeping a reef tank using tap water, I'd get it thoroughly tested first. And be aware the water companies put different stuff in it all the time, your tap water this month maybe different in 3 months time!

dansreef · Mar 4, 2018

In my town, we have actually pretty good quality water. If I had a water report, I would share. Even still, I recall reading about all sorts of contaminants in the water that fall below government regulations. On my RODI system on Jan 30th, I replaced all media, blocks, pre and even the membranes. I have two large reef systems running. So, I make a fair amount of water. With a little over a month's worth of filtration... the pristine white pre-filter now has an orange tint to it. The inbound TDS runs a little over 300 on my meter... my RODI then gets the output down to 0 in the TDS. If I take a close look... there is a fine sand, assuming a silicate of some sort, that collects in this section with the pre-filter. After only a month's worth of filtration. This all on a water system that is really pretty decent and a water department that gets awards on a regular basis.

I am not saying it cant be done. I had a 2 - 1/2 gallon with a condy anemone and a clown in college back in the mid 80's. I topped it off with tap water. I kept the nem and fish for almost 3 years. They did fine. With the availability of better sources of water, why run the risk.

rock_lobster · Mar 4, 2018

Randy Holmes-Farley said:
There will be evaporation (must be) if you have adequate aeration. All of the air you pump in will become saturated with water and it evaporates away in that way. That said, you may have reduced evaporation but inadequate aeration and I'd be worried about that aspect.

The main problem is copper, IMO.

In a small tank with little evaporation, if you don't want to buy an RO/DI, then get it from an LFS or buy purified water from a store. Distilled, for example. The cost will be minimal if evaporation is as low as you suggest.

Yup that pretty much sums it up. Evaporation is maybe 1cup-2 cup week. But yes definitely not worth the risk. copper in drinking water upper limit is 1.3ppm is far beyond toxic levels.