Do you use tap water?

[Jeff V]

I started with tap water and switched to RO/DI during a bad cyno outbreak for a month or so, but I got tired of messing with it and just went back to tap water.  My tank seems fine though.

Of course, I only have LPS, live rock, and fish, but each has done well.

Biggest thing I noticed with ro/di was lack of diatoms.

Is ro/di really a big deal?

[lazylivin]

Under intense lighting tap water can lead to lots of nuisance algae. However under Power Compacts and w/hardy corals many have been successful with tap water. Your case in point. tank looks great!

[Jeff V]

nuisance algea being like hair algea?  I assume the phosphate levels are higher in tap water? 

[Logzor]

Your tank is gorgeous. Lots of people can surprising do fine with tap water. It can actually be very clean in some townships!

[Reefd Up]

I used de-chlorinated tap water for about 6 months, then I broke out with the worst hair algae ever (well, my tank did...not me...that'd be really gross!)  It took a long time to get all the phosphates out of the tank (they can build up pretty bad...in the rocks and stuff).  I lost a lot of corals too.  But, Huber Heights has terrible water. 

If you plan to keep SPS, I'd permanently switch.  Otherwise, you might get away with it...or you might pay for it big later.  There are a few people on here successfully keeping tanks with de-chlorinated tap water.

[jungliztkruger]

I too successfully grew hair algae with my tap water. I purchased an RODI unit a few weeks back and have started the uphill battle against the phosphates. When i got the RODI unit I also received a TDS meter (total dissolved solids) and my tap water was about 158 parts per million tds that i was concentrating in my tank every time i used it for top off.

[Jeff V]

I must be pretty lucky then with my water.  I'm in washington township.  I am running a refugium though, which is probably competing and not letting hair algae grow.

[Hunter21]

I'm on well water so I can't use my water so I use walmart's distilled water till I can get my RO/DI unit fixed.

[Blown76mav]

When I started with this hobby/obsession a good buddy told me NEVER use tap water.  So I listened to him and bought a RO/DI unit and luckily never had a breakout of hair algae.  Great advise.  I don't know if I would want to risk a chance of something like that down the road, I've heard horror stories about removal.  Not saying it can't be done with tap water, but if you have the RO/DI unit why not use it.  I would think using  RO/DI water would be easier than tap, you don't have to add anything to it to make it work.  Are you sure the cyno outbreak wasn't from the Tap water? 

[rmstevensiii]

Your tank, your call.  I've run my tank on tap water from day 1... in 2003.  I know that it's a touchy topic for most, but it can be done. 

My .02

[Joel]

Very few have gotten away with using tap water indefinitely and had desirable results. Sure it can be used with little or no apparent signs of problems but typically it will eventually catch up with you. A situation that happens that I don't think many are aware of is when evaporation happens, water is the only thing leaving the aquarium. All the undesirable disolved minerals, chemicals & compounds in our tap water stays in the aquarium. Each time you top off your aquarium with more tap water, these undesirable elements are being concentrated in the aquariums water. In other words, the somewhat safe, low levels of "bad stuff" in our tap water can get concentrated to much higher and often unsafe levels eventually, So you may not see a problem early on but in time it often becomes a problem. Compair this to taking a glass of water an putting it on your counter and letting it evaporate a little and keep toping it off with tap water. In time, because water is the only thing leaving the glass, the levels of minerals and other compounds will be so high that it would not be drinkable. The same thing can happen in your aquarium.

Using dematerialized (ro/di) water is your best option, it will significantly decrease the odds of algae and other potential problems in the future. The minor inconvenience is small by compared to the major loss that can occur due to water and environmental problems.

Also, using distilled water is risky due to how it was distilled. It is my understanding that copper tubing is often used in the distilling process and may leave trace amounts of copper in the water.

Joel