Using tap water rather than RODI water

[DickTest]

Before I continue - I KNOW RODI water is best practice.

I have had fresh water tanks for over 2.5yr now and I am lucky enough to have tap water that fit within the parameters of freshwater fish keeping, I do weekly water changes and the fish and plants are thriving without adding any products to clean the water.

My question is; If it is good enough for the fresh fish, would using the same tap water for top ups be acceptable? I wouldn’t try my luck on full water changes as that would be a larger change to the water conditions. How risky is this and what would be the problems?

[debbeach13]

I ran my evo 5 tank using tap water treated with prime for over a year and it did great. Having said that I constantly reminded people that it is not recommended. A link to that journal is in my signature (365 contest). Although this tank did great it was mostly softies that many consider to be like weeds. Other members will warn you of all the dangers of doing this. Take the warning seriously. Your tap water may even test pretty good for TDS, PO4 and NO3 but that could change tomorrow. Good luck in whatever you decide to do. Happy reefing!

[DickTest]

6 hours ago, debbeach13 said:

I ran my evo 5 tank using tap water treated with prime for over a year and it did great. Having said that I constantly reminded people that it is not recommended. A link to that journal is in my signature (365 contest). Although this tank did great it was mostly softies that many consider to be like weeds. Other members will warn you of all the dangers of doing this. Take the warning seriously. Your tap water may even test pretty good for TDS, PO4 and NO3 but that could change tomorrow. Good luck in whatever you decide to do. Happy reefing!

thanks deb,  so it's not the end of the world if I was to use tap water but as a matter of making sure everything is perfect; ROI water is the best option. 

[debbeach13]

Yes. Especially if you want more than softies or very hardy corals.

[DickTest]

Just now, debbeach13 said:

Yes. Especially if you want more than softies or very hardy corals.

well atm just looking to try my hand at it - starting small and working my way up. some zoa's, kenya tree, Xenia and some clowns?

[debbeach13]

What size tank are you thinking about?

[DickTest]

Fluval spec 19l - I know its small, but using this as a test bed to see how marine keeping goes. will most upgrade in the near future.

[Tamberav]

It can work but everyone's tap is different and it can even change seasonally. You could always buy gallons of distilled water at walmart or the grocery store and use that instead if you find out your tap is producing annoying results (like ugly diatoms). 

[DickTest]

True - my local fish store has both ROI water and salted - I will buy the water (as investing in a ROI filter is large expense for such a small tank) for water changes but will dose/top up evaporated water with tap and see how the tank does. When i get a bigger tank and start playing with hard corals and more exotic fish then i will look into ROI water. thanks guys

[Tamberav]

That seems like a good trade off since water changes will remove the buildup of things from the tap water

 

As long as the LFS has good water... some LFS are terrible about changing their RODI filters.

[debbeach13]

1 hour ago, DickTest said:

some clowns?

Not a good idea in a 5 gallon. 

[mcarroll]

1 hour ago, DickTest said:

True - my local fish store has both ROI water and salted - I will buy the water (as investing in a ROI filter is large expense for such a small tank) for water changes but will dose/top up evaporated water with tap and see how the tank does. When i get a bigger tank and start playing with hard corals and more exotic fish then i will look into ROI water. thanks guys

In a 5 gallon tank (any cover?), you aren't talking about a large volume of evaporation.

 

Point being that you aren't saving any significant amount of money by using tap water for ATO, even if it's possible.

 

Even on my open-top 125 gallon running a protein skimmer, I only go through about 5 gallons a week.  Your rate should be an order of magnitude or so less.

 

Just a thought.  👍

 

BTW, there ARE ways to save money in this hobby....but this isn't a great one.

[Tamberav]

Is it to save money? I just figured it is because they wanted to haul less water home. 

[DickTest]

19 hours ago, debbeach13 said:

Not a good idea in a 5 gallon. 

not going to be a long term tank - will upgrade later

[Kindanewtothis]

For 5 gallons ? What about distilled ?

[Tired]

Distilled water is pretty much the same thing as RODI. Different production methods, but the end result is water without other stuff in it either way.

[mcarroll]

1 hour ago, DickTest said:

not going to be a long term tank - will upgrade later

If you want clownfish, a 10 or 20 gallon would be a much better tank size, and already a small tank for the size of the fish – they get around 3" long, depending on species.   Clownfish happen to be mostly-sedentary fish, relatively speaking, so they are compatible with the lack of space.   5 gallons is way too small though.

 

Wait on the fish until you do the upgrade.

[InAtTheDeepEnd]

I tried using tapwater in my 5g. It ended terribly and quickly. The water out our taps is filthy and unpredictable and our saltwater friends like a clean, stable home. In the short term you might save £5 on water but in the long run you'll lose livestock, money and your enjoyment. Just use RO honestly. My lfs do a deal whereby if you spend £5 in store your water is free. 

[InAtTheDeepEnd]

Also, please do not put even 1 clownfish in a 5gal. You could have a coral goby maybe, or one or two of the other nano gobies (eviota, trimma). But really, it is too small for anything bigger than 4cm imo

[DickTest]

1 hour ago, InAtTheDeepEnd said:

I tried using tapwater in my 5g. It ended terribly and quickly. The water out our taps is filthy and unpredictable and our saltwater friends like a clean, stable home. In the short term you might save £5 on water but in the long run you'll lose livestock, money and your enjoyment. Just use RO honestly. My lfs do a deal whereby if you spend £5 in store your water is free. 

I get your point - and as I said at the beginning, RO is the correct method. I just wanted to know the reasons why (I am lucky to have stable tap water) but I realise that using tap water in the long term is not recommended.  Where is your Fish store? - the best deals I have found is online - so not something I could just grab on the day.

[Tamberav]

You can just buy regular distilled water (not the kind with minerals added back for taste) for the tank. I used to buy that at the grocery or walmart when my only tank was a 12g. 

 

The thing about 5g is once you got the rock and stuff in there... it doesn't hold anywhere near 5g anymore. I have done it in the stort term for clowns when I needed somewhere to put them for a few months but ya.. they are little poo machines and fairly active. 

[StevieT]

Maybe this was already suggested but I figured I would type to a user name like this.  And they potentially have a similar business interest

 

Test your tap water.  Send it in and find out what is inside, this is really cheap.  There is some amazing tap water out there that is consistent in a few month period

  on the other side
    
    Risk is up to the user.  $200 in-house RODI + labor VS $1k aquarium sustaining the hundreds potentially thousands of lives that you raped from the ocean

 

   





 

[InAtTheDeepEnd]

26 minutes ago, StevieT said:

Maybe this was already suggested but I figured I would type to a user name like this.  And they potentially have a similar business interest

 

Test your tap water.  Send it in and find out what is inside, this is really cheap.  There is some amazing tap water out there that is consistent in a few month period

  on the other side
    
    Risk is up to the user.  $200 in-house RODI + labor VS $1k aquarium sustaining the hundreds potentially thousands of lives that you raped from the ocean

 

   





 

the thing about 'amazing tap water' is one day it can just change and become totally crappy....and unless you're testing every time you turn the tap on you won't necessarily know until something goes wrong. I've had water suddenly come out my tap at 0.5ppm nitrite before now. (Obviously nitrite isn't relevant to SW systems but it just goes to show how much, and how quickly, it can go from being okay to being really not okay.)

[banasophia]

I agree with others that RODI or distilled water are probably a much better way to go than tap water for topoffs in most cases.

 

Here are my recent TDS measurements for my tap water vs distilled:

 

I don’t know what’s in my 69 ppm of TDS, and 69 ppm may be a tiny amount. But it’s not 69 ppm being added once… you have to keep adding topoff water daily as water continually evaporates from the tank… and then only pure H20 evaporates from the tank leaving behind the impurities. Each time you add more topoff water, you will be adding more impurities which can build up more and more in the tank as time goes on.
 

Maybe the impurities will be partially removed during water changes, but since you’re doing partial water changes some will be left behind. It’s possible the impurities could also be filtered out by your filter media, but I’m not sure about that… probably depends on the impurities and what filter media you’re using. Could the impurities get absorbed by your rock or settle in the sand? Not sure, but I would be worried about that possibility. It seems that it would be hard to anticipate whether one’s particular built up impurities would have an impact on future fish, corals, and other livestock. I personally wouldn’t want to take a chance… certain corals and inverts can be very sensitive.
 

You could get your tap water tested as someone else suggested… at least that way you’ll know more about what contaminants are in your water. But as someone else mentioned, your tap water could suddenly and unexpectedly change. Our water company just did some work on the hydrants in our neighborhood a few weeks ago and our water started running brown and when I called them they told me it was sediment from the pipes and not to drink it. 
 

I use distilled for my topoffs. Gallon jugs cost $1-2 at my local grocery store but I now get 5 gallon jugs of arrowhead water delivered because I can return the jugs for reuse in order to reduce plastic waste. 
 

In fact, before I got an RODI filter, I used to mix my saltwater using distilled. Now I only get one jug once/month.

 

 

[Tired]

You can get an RO Buddie brand unit for something like $70, if the cost of the RODI unit is a concern.