RO Water

Wonf · Jan 11, 2017

I've just realized I may have been using the wrong water this whole time, thinking it was RO/DI when in fact it's just RO.

We use a counter top RO unit for our drinking water, so I've just been filling spare 5 gallon jugs for use when needed. So far, its worked out... BUT its NOT RO/DI....

What are the potential downsides of using just RO water? Should I be treating the water with anything before using?

My unit says there's some "extra" filtration, but nothing about it being DI. Here's a link to its description:
http://coway-usa.com/index.php?route=product/productp&path=59_61&product_id=56

JoshH · Jan 11, 2017

RO does not remove ALL TDS from your water only most. So if you're looking for 100% clear water RO won't cut it on its own. DI filters are not used for human consumption so I'm willing to bet they are some kind of particulate filter for "Extra filtration".

Wonf · Jan 11, 2017

So... what exactly have I been doing to my tank as far as water quality? I've only been testing the basic/newbie stuff (pH, Ammonia, Nitrite and Nitrates) and never really had problems. What will/can small amounts of TDS do?

JoshH · Jan 11, 2017

That I am not sure of myself, someone with more experience than me with water paramiters will have to answer that.

redfishbluefish · Jan 11, 2017

That is not producing DI water. In addition, the storage tank allows "break through" TDS to accumulate in the tank.

Not knowing anything about that unit, I went to your link. I was shocked at the cost of replacement filters. They are ridiculously expensive. I pay about 25 bucks for one new sediment filter and two carbon blocks...replaced yearly.

You'd be better off using that purifier for drinking water and picking up something like THIS from Spectrapure for your tank.

JoshH · Jan 11, 2017

redfishbluefish said:
That is not producing DI water. In additon, the storage tank allows "break through" TDS to accumulate in the tank.

Not knowing anything about that unit, I went to your link. I was shocked at the cost of replacement filters. They are ridiculously expensive. I pay about 25 bucks for one new sediment filter and two carbon blocks...replaced yearly.

You'd be better off using that purifier for drinking water and picking up something like THIS from Spectrapure for your tank.

This is the exact system I have for mine as well, NOT for drinking though lol

Wonf · Jan 11, 2017

You're right, that is the system I've been using as drinking water prior to starting this hobby... and figured the RO water would be fine for my tank.

So again, what does using TDS contaminated water potentially do to my tank?

Betty1964 · Jan 12, 2017

The RO filter removes contaminants and bacteria from your water. The DI removes heavy metals. These metals can be fairly harmless or deadly, depending on your water source. Metals can also build up in your system over time.

That being said, RO is better than tap water. The thing with reef keeping is that we are constantly learning. None of us has it down perfectly...so, give yourself a pat on the back for the RO. Find a decent RO/DI filter that is dedicated for your fish, along with a two barrels (lots of folks use the brute trash cans) if you have room. If you don't have room, use a couple of 5 gallon buckets. Fill one barrel with DI water for your top offs. Use the other barrel for your salt water: having a barrel of salt water mixed will save your butt in an emergency.

Frop · Jan 12, 2017

When I started my tank they said the minerals and stuff in tap water would cause algae. Also chlorine isn't good. Actually I checked my "RO/DI" water I got from the pet store and it showed a TDS of 10 which was alarming to me... because it should be 0. so far the 10gallon tank is fine.

PatW · Jan 12, 2017

I have heard of people using tap water in their aquariums with good results. Of course, these are those very fortunate people who have very low TDS tap water.

My tap water is about 150 TDS. The water comes out of my RO membrane at 2 TDS. It comes out of my DI canister at 0 TDS.

Now if you are running low TDS water and making salt water from it, you might be just fine. You would get potential buildup of unwanted ions from your top off water but if you did regular and frequent water changes, it might never be a problem. The problem with this is you just never know just what is in that small fraction of TDS. It could be lead, arsenic, copper, nitrates, phosphates or something else that could cause serious problems.

An inexpensive RODI unit can be had for around $100. It is really convenient to have your own source of pure water. Another thing is I can control the quality of my water. If I buy water from any other source, I just do not know what I am getting.

redfishbluefish · Jan 12, 2017

Here's the issue.....evaporation.

If you could set up your tank with just RO water, and nothing changed, you'd be fine. However, their is change, and that change is evaporation. I have a 90 gallon DT and loose 1 to 1 1/2 gallons per day. Dissolved solids don't evaporate....they stay in your tank.....and now start to build up. I think you see the picture.

RoyinSpain · Jan 14, 2017

Yes, water changes don't help at all if you are simply using the same high TDS water to replace that evaporated or to change water... In fact you just make it worse...