Using tap for reef tanks

zdrc

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I'm in the process of setting up my first reef tank, and I am wondering if I can get away with using tap water instead of RODI water.

I live in Colorado, which means I'm at the top of the watershed, and the tap water quality seems generally quite good. Using API tests, ammonia, nitrite, and nitrate are all at undetectable levels, carbonate hardness (kH) is 1-2 degrees, general hardness (GH) is 3-4 degrees, and pH is around 7.4-7.6. I use tap on all my freshwater tanks without much of a problem. I have no idea what calcium, magnesium, and phosphate are.

I think I'll buy more tests (e.g. calcium, magnesium, and phosphate) and a salt mix, mix up some saltwater with the tap, and test it. If everything looks good I'll probably try using tap for the time being. I'm hopeful that the low initial alkalinity will mean the mixed saltwater will be pretty low. I use seachem prime as a dechlorinator.

The only things I'm worried about missing are copper and silicon. Local water quality reports say that the 90th percentile for copper measurements done in the water district was ~0.1 mg/L. This seems somewhat high. However, I've been keeping dwarf shrimp and pagaoda snails for years in this tap water which seems to indicate that the copper levels aren't too bad? For silicates I have no idea. My freshwater tanks all get diatoms when they first start up, but they clear like normal as the tank ages same as any other tank.

For reference, I only plan on keeping soft corals and LPS in this first tank.
 

Chrisv.

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Honestly, the hobby is hard enough. Three months in, when you're facing challenges (as everyone does) you don't want to wonder if the tank was screwed from day one due to the water. I would not recommend using tap water. Begin the journey on the right foot.
 

mdb_talon

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For all the money you spending on tests could have bought an rodi unit and had no concerns on water.

Personally the things i can easily test for are the least of my concerns with tapwater. At a minimum i would get an icp test and see what that says.
 
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zdrc

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For all the money you spending on tests could have bought an rodi unit and had no concerns on water.

Personally the things i can easily test for are the least of my concerns with tapwater. At a minimum i would get an icp test and see what that says.
But I love testing the water! If you can't test it you can't understand it.

What else would you be worried about?
 

Jedi1199

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Since I love to prove doubters wrong..


Set up a pico tank.. basic 5 gallon tank with backfilter and stock light. Mix your SW with your tap water and drop in a few snails and maybe a peppermint shrimp. If they are all dead within a few weeks... well the doubters were probably right.. if not, you have a good idea that your tap water is ok, plus a nice pico tank to boot.
 
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zdrc

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Since I love to prove doubters wrong..


Set up a pico tank.. basic 5 gallon tank with backfilter and stock light. Mix your SW with your tap water and drop in a few snails and maybe a peppermint shrimp. If they are all dead within a few weeks... well the doubters were probably right.. if not, you have a good idea that your tap water is ok, plus a nice pico tank to boot.

Honestly, this is what I'm gonna do. My tank is just a 12 gallon aquapod. I can make all the mistakes. If it really isn't working with the tap I'll switch to RODI, but I think it would actually be nice to at least try. There is no immediate obvious reason my tap won't work based on the tests I've already done. Of course, if something seems really wrong with the water after mixing (e.g. the calcium ends up being 800 or something) then I'll get an RO unit.
 

damsels are not mean

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Do I think it will succeed? Probably, but the reason RO/DI is so important is that it eliminates variables (especially that you cannot control or always know about) when troubleshooting. Lots can be in the water you can't test for that might accumulate over time plus some things won't necessarily show in an ICP test if they are seasonal or random like fertilizers leeching in or in some cases chemicals added during treatment of some sort of bloom.
 

fluked

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I used dechlorinated tap water on my second tank at the start because i was lazy af. Besides maybe some extra algae it didnt kill anything.
If i was going to do it long term, i would do an icp test on it, check your levels of copper and other things
If they are okay
Then yolo
 

Jedi1199

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OK.. back in the early 90s I built a SW fish only tank using tap water and purple IO salt. I didn't know anything then about copper toxicity or algal bloom from heavily saturated water. There was no internet and viable source material on SW aquaria was scarce at best.

I ran a successful tank for almost 2 years with a Hippo tang, Undulate trigger, Volitan Lion and even a coral banded shrimp. The tap water I used could at best be described as "chemical soup". In my opinion is was barely fit to bathe in let alone consume.

I was still able to maintain a healthy tank with this horrific source water. It wasn't until I got a clownfish and wanted an anemone for his home that I learned of my folly. That Nem was dead inside of a week.

I spent the next few months pouring money into additives to remove copper before finally giving up on SW and going back to fresh.

My point is, Tap water is not "necessarily" lethal to a SW tank. It CAN be done, but bear in mind, not all fish are able to tolerate it, and MOST inverts will likely be singing their swan song in short order.
 

damsels are not mean

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My first tank ran for several years on just tap + prime. Buying from the LFS was annoying and expensive and so was an RO/DI so that's what I did. I grew lots of corals in there for a while and no real issues. I didn't do any SPS successfully but I think that was mostly lighting. They just "existed" in there but didn't grow much and stayed brown. Toxicity of the water didn't seem an issue. This is water from the Chicago area.
 

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My first tank ran for several years on just tap + prime. Buying from the LFS was annoying and expensive and so was an RO/DI so that's what I did. I grew lots of corals in there for a while and no real issues. I didn't do any SPS successfully but I think that was mostly lighting. They just "existed" in there but didn't grow much and stayed brown. Toxicity of the water didn't seem an issue. This is water from the Chicago area.
Chicago has one of the best, if not best, water treatment plants in the country.
 

gbroadbridge

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I'm in the process of setting up my first reef tank, and I am wondering if I can get away with using tap water instead of RODI water.

I live in Colorado, which means I'm at the top of the watershed, and the tap water quality seems generally quite good. Using API tests, ammonia, nitrite, and nitrate are all at undetectable levels, carbonate hardness (kH) is 1-2 degrees, general hardness (GH) is 3-4 degrees, and pH is around 7.4-7.6. I use tap on all my freshwater tanks without much of a problem. I have no idea what calcium, magnesium, and phosphate are.

I think I'll buy more tests (e.g. calcium, magnesium, and phosphate) and a salt mix, mix up some saltwater with the tap, and test it. If everything looks good I'll probably try using tap for the time being. I'm hopeful that the low initial alkalinity will mean the mixed saltwater will be pretty low. I use seachem prime as a dechlorinator.

The only things I'm worried about missing are copper and silicon. Local water quality reports say that the 90th percentile for copper measurements done in the water district was ~0.1 mg/L. This seems somewhat high. However, I've been keeping dwarf shrimp and pagaoda snails for years in this tap water which seems to indicate that the copper levels aren't too bad? For silicates I have no idea. My freshwater tanks all get diatoms when they first start up, but they clear like normal as the tank ages same as any other tank.

For reference, I only plan on keeping soft corals and LPS in this first tank.

To put it simply, while you can get away with tap water sometimes, in every case I know of it leads to problems down the track, whether it be in 3 months or 12 months.

The salt that you will mix has been designed to be disolved into RO/DI filtered water. It expects a blank canvas.

By introducing irregularities into the mix you will without doubt have problems later that you could have avoided for a very small initial cost of a filter. If you don't want to buy a filter, buy Distilled water from a big box store and use that.

As another poster said, this is a difficult and expensive hobby. You don't want to make things any more difficult for yourself and end up spending a big bucks later trying to fix things.
 

LgTas

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I live in Tasmania so probably not a great yard stick but my wife works for the Water Board as a chemist and I submit tap water as my "RODI" sample as an extra form of monitoring.

ICP tests have never shown anything to be concerned about (confirmed by Randy). I do only use tapwater for top ups with natural sea water for major water changes. Have three tanks all older than 12 months (mixed nem, sps dominant and softy sea horse) and don't have any issues with it. No skimmers or mechanical filtration on any of the tanks but very healthy fuges.

Saying that, if I lived somewhere more populated with worse water treatment then I'd be inclined to fo RODI.
 

ss30

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I'm in the process of setting up my first reef tank, and I am wondering if I can get away with using tap water instead of RODI water.

I live in Colorado, which means I'm at the top of the watershed, and the tap water quality seems generally quite good. Using API tests, ammonia, nitrite, and nitrate are all at undetectable levels, carbonate hardness (kH) is 1-2 degrees, general hardness (GH) is 3-4 degrees, and pH is around 7.4-7.6. I use tap on all my freshwater tanks without much of a problem. I have no idea what calcium, magnesium, and phosphate are.

I think I'll buy more tests (e.g. calcium, magnesium, and phosphate) and a salt mix, mix up some saltwater with the tap, and test it. If everything looks good I'll probably try using tap for the time being. I'm hopeful that the low initial alkalinity will mean the mixed saltwater will be pretty low. I use seachem prime as a dechlorinator.

The only things I'm worried about missing are copper and silicon. Local water quality reports say that the 90th percentile for copper measurements done in the water district was ~0.1 mg/L. This seems somewhat high. However, I've been keeping dwarf shrimp and pagaoda snails for years in this tap water which seems to indicate that the copper levels aren't too bad? For silicates I have no idea. My freshwater tanks all get diatoms when they first start up, but they clear like normal as the tank ages same as any other tank.

For reference, I only plan on keeping soft corals and LPS in this first tank.
First off API Test Kits are not very accurate.

Second thing the water you tested today will it be the same in a week or a month or will the water authority added something because of a problem they have encountered with the supply which could them wipe out your tank.

Third thing why ask a question and when you get told don't do it you just say f**k it I'm going to do it anyway!
 
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ss30

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I ran tap water reefs for five years or so in the mid to late 90s. There was a substantial decrease in "weird stuff happening to the tank" when I got a RODI. But since OP already decided to do a tap water tank, this whole thread is a bit useless.
Yeah completely pointless!
 

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