View Full Version : Tap Water in a Coral System...?

07/14/2014, 07:42 PM
After reviewing a thread started by Paul B, which you can find here (http://www.reefcentral.com/forums/showthread.php?t=2421363), I started to question if I need to do more for my tank in terms of water quality. But the thing is, I have been using de-chlorinated tap water for almost 4 years, and I have never had a problem. No algae explosions, no diatoms, no sick fish, nothing. Unless you count the clarity issue that I had when I was running a canister, but that cleared after I started my sump, I have had 0 problems.

Now I will establish this: I have not had any corals or any sensitive fish in this tank. But now that I plan to start getting into corals, I decided to invest in an RO/DI system. But with this thing, as confusing as it was to set it up and get it to the point of producing water with the crappy water pressure that I have, I can't help but wonder how the system would fare if I keep using tap water. Yes, I know that there is a load of stuff to take into account with water quality and coral-keeping, but Paul's post has thinking about if they would adapt or not. And yes, I know that I will need a booster pump soon.

Now this is just a random rant, but maybe someone has some knowledge to pass. Maybe there is someone using tap water in a coral system. :hmm4:

07/14/2014, 07:55 PM
I just bought my first RO unit. I have gone tap water only for almost 10 years. I bought the RO to use in a tank that I have not set up yet and to see what all the fuss is about. None of my corals were all that difficult to care for. The most sensitive thing I had was a clam for 2 years until I sold him.


07/14/2014, 10:37 PM
A reef tank can certainly be run with tap water, but the big "if" is if your water is free of harmful chemicals. Most of us have tap water that is far form usable in a reef tank, but yours certainly could be one of the exceptions. Copper is the biggest concern assuming your tap water is low in nitrates and phosphates, but there are many other pollutants that can build up over time and then cause a sudden decline in your tank. Most of us even with high quality tap water won't take the risk when we have hundred or thousands of dollars in corals at risk.

07/14/2014, 11:45 PM
If u can get a Tds meter and ck ur water u will know about ur water condition and i kept zoas and plays for 2 years with just tap water then I started sps and had to get rodi unit

07/15/2014, 02:39 AM
My water is high in phosphate and alk.

07/15/2014, 03:11 AM
Check out the water report for your area.

07/15/2014, 03:19 AM
It just depends what is 'in' the tap as all tap is very different. It even makes a difference if you use the water right when it comes out of the tap or if you wait a few minutes so it is not sitting in possible copper pipes or other things. I use tap. My TDS is about 20 right now. That is pretty good for tap....but those 20 could be benign or something bad.

So far I have been using it a year and not had any problems. Do not rely just on TDS because it could be 20ppm of something dangerous. I would get a city water report (but you still will not be 100% sure since it sits in pipes). I say if you have relatively inexpensive corals it is worth it to give it a shot, just for how much easier it is to turn a tap than pay to keep up an RO filter, not to mention how slow they are. If you have precious expensive corals you should just go with RO from the start.

My 2 cents, and my tap tank.


07/15/2014, 05:06 AM
I used tap water for over 20 years and never saw a problem that I could directly associate with it's use. I made the switch a couple years ago and have found that many problems that I just assumed were a normal part of the hobby have pretty much gone away. Within a few months of starting it's use, everything looked much better, at least IMO.

As a bonus, I ran a line from the the ro output to my refrigerator so now I don't have to waste big $$$ on filters for it anymore!

07/15/2014, 07:18 AM
I've used tap in FO tanks in the past, but I would occasionally have an algae bloom that I'd have to fight back. Now that I have a reef, I use RODI

IMHO, the biggest risk isn't the tap water itself but the potential inconsistency of the that tap water. Maybe it's great for a couple months, and then your water provider decides to dump a bunch of stuff in for some reason etc..

I have had much less nuisance algae since I started using my RODI...

Randy Holmes-Farley
07/15/2014, 03:38 PM
FWIW, I discuss the issues that would concern me most in tap water here:

Tap Water in Reef Aquaria

If u can get a Tds meter and ck ur water u will know about ur water condition

I don't see how knowing the ppm TDS of your tap water is useful. 1000 ppm TDS might be fine if it is mostly stuff already in seawater at high levels, and 5 ppm TDS could be terrible if it contains substantial copper from your own pipes.

07/15/2014, 10:32 PM
I have read the reports for my area. There is about 49 ppm TDS, and no copper unless a sample was collected from a source with eroding plumbing. Contrary to belief, out of all of the places that I have lived, NYC has the best water quality that I have seen. The water comes from up-state. If it came from the rivers here, even though they are pretty clean for an urban area, we would be in trouble.

But, I have switched to RO/DI. Just finished a water change with RO/DI and Brightwell salt, and the ATO is full of pure water.

07/15/2014, 10:38 PM
You can get away with a lot of the simple fish and corals using tap water. I did it for years but noticed that whenever I tried to keep some of the more sensitive fish or corals they would die. Ever since I started using the RO/DI unit havn't had a problem keeping any fish in my tank. I noticed when adding fish since switching their stress levels were far less when adding. As for corals much better but so many more factors come in to play with them. Anyway, you can get an awesome adjustable 7 stage RO/DI off ebay for 80 bucks