Tap water vs r.o

Reef_rookies

Reef_rookies

New member
I understand r.o water is supposed to be better to use for water changes/top ups but is it okay to use tap water as long as you use water conditioner?
 
Depends what's in your tap water. Quality water conditioners remove chlorine, chloramine, and ammonia. They claim to "bind" heavy metals, but it's hard to say how well. They don't do anything for pesticides, antibiotics, phosphates, and a million other things that don't hurt people, but might not be ok for fish or coral. It's a big risk. Also, salt mix is balanced to be added to pure water. If your tap alk is at 8 instead of zero, and your salt is at 14; your adding water to your tank at 22 dkh. That's no bueno
More info here http://www.reefcentral.com/index.php/rodi-faq
 
CStrickland said:
Depends what's in your tap water. Quality water conditioners remove chlorine, chloramine, and ammonia. They claim to "bind" heavy metals, but it's hard to say how well. They don't do anything for pesticides, antibiotics, phosphates, and a million other things that don't hurt people, but might not be ok for fish or coral. It's a big risk. Also, salt mix is balanced to be added to pure water. If your tap alk is at 8 instead of zero, and your salt is at 14; your adding water to your tank at 22 dkh. That's no bueno
More info here http://www.reefcentral.com/index.php/rodi-faq
Click to expand...

Thanks that helped a lot....how much does it typically cost for an r.o system to supply an aquarium?
 
20 years ago I might have said "Yes" but even back then I stopped using tap water and conditioners. Today I'll say "No Way" as RO/DI units are pretty cheap and they work the best. I won't even drink my city water, so why would I put it in my tank?
 
Get a copy of your local water report. I was going to use conditioned tap water instead of RO but changed my mind after reading my water report.
 
Reef_rookies said:
Thanks that helped a lot....how much does it typically cost for an r.o system to supply an aquarium?
Click to expand...

After a lot of research I bought this one http://spectrapure.com/Refurbished-90-GPD-RODI-System but I waited for a sale to come around so I think it was $150 after shipping and all.

When you shop around, stay away from units that:
- produce very slowly (gpd is the best case scenario: under perfect conditions a 25gpd unit will literally take an hour to make a gallon of water. Conditions are rarely perfect so likely even longer)
- use no-name membranes
- have less than 4 stages. You want at least: sediment, carbon, membrane, DI
- use proprietary filters / carbon that you have to buy from that company at a premium when it's time to replace
- dont have a pressure valve
- have bad reviews from people you trust (most of the reviews on like Amazon are folks who never had a rodi before. What do they know? Better to listen to experienced reefers on sites like this)
- lack access to customer service. It's a pretty complicated machine, you want to be able to reach a tech if something goes sideways or you need to customize for your particular tap water sitch
 
You have to watch cheaper ro systems, at the very least they use crap filters which will alow more to pass and need to be replaced more. You don't need the extra gauges( just nice to have if you use it a lot) and only need to 5/6 if you have chloramines in your city water. As others have said get a local water report and make a decision based on that. Personally I live in NJ, we used to have really bad water and it was linked to cancer, somehow we now have very good water but I'm gonna assume its extra chemical filtration and get a 6 stage. :)
 
It also depends on what your tank is going to be -- fish only tanks can use tap water. From experience (my) tap water is no good for any inverts including corals. I wouldn't risk setting up a reef tank using tap water, although many here have done so.
 
NYC has the best water in the country and I still use a RODI system. It comes from a great source. Only chlorine and fluoride is added. It is even UV sterilized.

It still comes out from the tap with 55 TDS, and with some phosphate, plus I don't know the condition of some of the pipes it flows through.
 
A fish only set up should be okay with conditioned tap water unless your local water comes from Flint, Michigan. For a reef setup, in the long run you'll benefit from RO/DI water. It just takes care of nuisance issues tap water can create: high phosphate and silica which usually lead to unwanted algae /diatom blooms.

When you consider how much we usually invest in our setups and the time we commit to them, the long term operating cost of a good quality RO/DI setup in my opinion is well worth the $$$ spent. To me an RO/DI unit is as important as good lights and a good skimmer and a reliable return pump.

As an aside, a refugia can help mop up undesirable components of tap water and other wastes your system may generate. They're great for biodiversity as well but they do take up space. If you can have a good sized refugia you might be able to skip RO/DI depending on the quality of your local water supply, but again, I prefer the certainty of chemically inert water produced by an RO/DI system.
 
I live in Atlanta and the water quality is pretty good. The TDS is at mid 40s straight out of the faucet. I am using common RO units and I get 1-3 TDS after filtering. I think my tap water is Okay for saltwater hobby but if possible RO still has advantages.
 
Generalizations are always 'dangerous', but I'd go so far as to say that modern RODI systems have been perhaps the most important addition to the successful maintenance of reef tanks than anything else (well, may be CA/Alk supplementation is a close second). Other than perhaps a FOWLR, I don't think most people will have long-term success without a good RODI system. Just think about how much evaporation occurs in a year, and what they will mean to the concentration of undesirables. I suppose somebody with really good raw water might be able to get by for a while, but mine routinely reads a TDS of 500.
 
Thanks everyone for your help! I think we will invest in one eventually because we are spending a lot on buying ro/di water from the store. Will have to do some research as to what is best for our 55 gallon reef tank.
 
A lot of reefers conflate tds levels with safety, but that is not wise. To say "my water is only __ tds so it's probs safe" is stupid. All tds tells you is how well a rodi is working, since it only tells you whether the water is pure, or not. The trick is in the not-ness. Are the tds dangerous compounds, or benign? If the produced waters not pure h2o, what other things are coming in that don't register as tds (virus, bacteria, large particles of who knows what, ions charged in a way that permits them to hide from a tds meter)?

Water can be very very dirty, and have low tds. Mine is, I get less than 100 tds off the tap but a standard sediment filter only lasts me 200 gallons. Water can be perfectly safe, and have high tds from minerals. The only thing you learn from checking tds is whether you rodi is working or not.

More here: http://reefkeeping.com/issues/2004-04/rhf/feature/index.php

EDIT: if you are going to buy rodi from a store, it's a reeeally good idea to just go ahead and buy your tds meter now. You can get an "HM digital pocket sized" on Amazon for like $20 to confirm your paying for pure water, and you'll use it once you pull the trigger on a unit of your own. Lfs get pretty cheap with filters and often take your money for sub-pure water
 
Last edited:
CStrickland said:
A lot of reefers conflate tds levels with safety, but that is not wise. To say "my water is only __ tds so it's probs safe" is stupid. All tds tells you is how well a rodi is working, since it only tells you whether the water is pure, or not. The trick is in the not-ness. Are the tds dangerous compounds, or benign? If the produced waters not pure h2o, what other things are coming in that don't register as tds (virus, bacteria, large particles of who knows what, ions charged in a way that permits them to hide from a tds meter)?

Water can be very very dirty, and have low tds. Mine is, I get less than 100 tds off the tap but a standard sediment filter only lasts me 200 gallons. Water can be perfectly safe, and have high tds from minerals. The only thing you learn from checking tds is whether you rodi is working or not.

More here: http://reefkeeping.com/issues/2004-04/rhf/feature/index.php

You hit the nail on the head, I have the same issue with low TDS but water sux. Also checking a large cities water quality doesn't always work. In our old work location which was near downtown with old water pipes I tested our water out of the tap and it had 10ppm of nitrates. Our new office location is near 0. And the high TDS in SA is caused by the Edwards Aquifer using Limestone as a water filter so that 400 tds is actually a bunch of calcium and other minerals that is not harmful, versus at my home where the water comes from east of town through miles of pipe and a combination of lake water with algae that grows great because most homes on that lake septic tanks drain into that lake. But remember that water is treated for human consumption before it gets to me!
Click to expand...
 
If you're already buying RO/DI from a store it's pretty easy to figure out how many months it will take for a good quality RO/DI unit to "pay" for itself. I bought a 4 stage that will produce 75 gallons per day and it paid for itself well inside of a year. I didn't factor in the gas and my time spent going back and forth to the store so to me, when factoring that in it's been a great purchase. Yes, over time you'll need to reinvest in new prefilters, resin exchange and ro membrane but again, that's probably still way cheaper than store bought and you save yourself the hassle of handling a bunch of 5 gallon jugs. It's also nice to be able to generate pure water on demand. You may not need a unit that does 75 gallons a day for a 50 gallon set up but it may be wise to buy a larger size than you need today if you think you might scale up some day. I started with a 55 and own a 210 today plus another 40 gallon freshwater planted setup that also uses RO/DI water. I'm glad I bought a larger unit out of the gate.
 
You must log in or register to reply here.

Similar threads

Jyetman
Why do my grandis palys look like this?
Replies
2
Views
898
Jyetman
Jyetman
Reignfire
Stray current
2
Replies
31
Views
1K
griss
griss
M
Rock hard crushed coral sand bed
Replies
8
Views
399
Jimbob
Jimbob
K
Seeding Marine Pure Gems
Replies
6
Views
308
SantaMonica
S
B
Left Tank for a long time, now want to reboot
Replies
8
Views
379
SantaMonica
S
Back
Top