Should I use an RO system?

[jlosey90]

Hello all!

I am having some issues with water hardness ( 425 TDS ) as well as some nitrite/nitrate problems. I believe the Nitrite and Nitrate issues can be fixed by cutting the amount of feeding. In the past I had issues with some bottom-dwellers not getting enough food. I've looked high and low for some ELI5 resources on RO filters, but I'm still in need of advice. Would it be beneficial to purchase an RO filter to reduce the hardness? How would that affect the other parameters in the tank (PH, etc)?

Also:
Being somewhat new to the area that has awful tap water, I want to set up an automatic water change system. However, I'm really unsure where to start. Any advice is appreciated!

[BrassFinger]

I have similar issues with water here from a hardness and pH standpoint. The hardness is more a nuisance since it covers everything in lime scale, but the pH is really difficult to deal with when it's off the charts on the high side and you try to bring home fish from the local shop with a pH close to neutral. I lost several tiger barbs due to pH shock before I realized what was going on and determined a pH change of 1.5+ is going to be hard to acclimate.

The solution was to purchase an RO system, specifically the "RO Buddie". It is a simple, low cost system that easily handles my modest requirements. I added a float valve and auto shutoff to the system so I don't have to monitor it as it fills the 7 gal. Aquatainer jug. I blend about 1/3 treated tap to 2/3 RO water right now and keep an eye on the pH and hardness of the tanks, adjusting the blend as needed. I don't target any specific hardness but I recall my tap water was in the 350 TDS range so the 1/3 - 2/3 seems about right and keeps the pH around 7.6.

At least I have city deep well (>1000 ft. deep) water, even though it does a good imitation of liquid cement. The folks with residential wells (100 to 300 ft. deep) around here have to deal with the extreme hardness and also have to deal with a lot of iron as well. Imagine drinking a cement/rebar smoothie....that's about what it tastes like!

Chris

[Bas Pels]

Whether an RO system would be needed or not will, amongst others, depent on your choise of fishes. However, don't expect adding an RO system te be all the work.

There are RO systems around which automatically mix the RO output with tapwater in a preset rate - one can add 10 % tapwater, or 80 % or whatever. But RO water is depleted of everything - that is, it does not buffer pH, it does not contain any oxygen - it is water, H2O and nothing more.

Therefore, for aquarium purposes one would need to bubble air for some 24 hrs through it, before using it in a tank.

Obviously, one can make a permanent waterchange system with a bubble-chamber in it, but that is rather complicated. It is, however, needed for your fishes - you don't want them in oxygen free water

[smitty]

But RO water is depleted of everything - that is, it does not buffer pH, it does not contain any oxygen - it is water, H2O and nothing more.

Bas many do not realize that. Glad you pointed it out.

[Narwhal72]

An RO does not remove oxygen from the water. In that respect it is no different from tap water. If you have to aerate RO water to restore oxygen you would also have to aerate tapwater. I am not saying that aeration is a bad thing but it's not really necessary. I store my RO in 50 gallon drums but I don't aerate it. Often I use it as soon as it has warmed up.

It does however remove all buffering capacity and about 99% of all dissolved minerals. You can mix a little tapwater back in to bring levels up or you can add trace element salts to bring up the TDS if you don't want to mix tapwater back in. Keep in mind that you will be adding back the unwanted elements if you add back tapwater. Some areas have high nitrate and phosphate which you may not want even at a reduced level.

All of my South American fish are on pretty much straight RO water with a little bit of trace elements added in. I use the RO wastewater for my African and harder water fish. Because my area has fairly hard water I also have tanks setup for fish I am getting ready to sell. I condition these fish from RO water to the local tapwater so they don't go into shock when sold or traded.

While RO is nice I do find that needing to store the water in large volumes before use is cumbersome. If you don't have a place to store the amount of water you need for a full water change readily available I would recommend passing on investing in an RO and just purchasing RO water from your lfs.

Andy

[bekateen]

What I'm about to say is not based on experience but on classroom/textbook info: I was under the impression that gases like O2 and CO2 we're not osmotically active and thus wouldn't be affected in RO systems. That said I do know that distilled water systems will degas the water during the boiling step and would deplete O2 and CO2, although these gases should reenter slowly during the cooling and condensation step.

I used to have a small under-sink RO system for my frog tanks at work (but no more since our new building is plumbed with an RO line), and never observed a problem with hypoxia, but to be fair I never tested O2 concentrations.

Cheers, Eric

[TwoTankAmin]

Lets not forget about systems with DI modules, which is what I use. The DI will remove ions such as nitrate. I use a 3-stage system with a carbon, RO and DI module.
When it is brand new my TDS meter will read 0. When it has been used for some time that number tends to creep up to 10 ppm from 0.

My tap is about 80 ppm TDS, pH 7.1. Last time I tested GH was about 5 dg and KH 3-4 dg. My goal is to produce lower TDS and to lower pH towards 6.0. I am using it for a tank for wild altums which also holds some rummy nose tetras and a couple of H. contradens. I may also use ro/di when simulating a rainy season for plecos. In order to keep on top of things, I have both a digital TDS/temp. hand held meter and a continuous monitor on the tank that reads temp., pH and conductivity/TDS. Without this is would be impossible to control things.

I normally use muriatic acid to help drop the pH, and then catappa leaves and alder cones to help hold it down between water changes. My mix is 50/50 ro/di and tap. I have learned is that acid water fish can handle a rapid large pH drop. I have lowered the pH in the tank by as much as 1.1 in under 5 minutes on a number of occasions with no ill effects. I would never try the reverse however.

Using ro water means more work. In order to maintain the 55 gal. tank, I have to premix the 20 gals for water changes. This tank takes more work per gal. to maintain than any of my other tanks. Only my old high light co2 added planted tank took more work per gal. (why I no longer have it). In my fish space the utility sink faucet is modified to accept a standard garden hose connection. So I bought this unit http://abundantflowwatersystems.com/


It comes ready to go out of the box with color coded lines and the intake (red hose) comes with a garden hose connection built in. I recently changed the carbon and ro membrane stages. It was a snap. I chose a portable system as space considerations made it impossible to do a permanent setup. It is a 75 gpd system, but to get the maximum output of most units requires a pump. Two other notes on this. Your water will batch faster if it has a bit of hot mixed in. I shoot for water in the low 70s F. You can also regulate the output somewhat by how hard you run the tap water. If you batch into a big can, slower flow can prevent flooding due to accidental overproduction. I have done that a few times......

Lastly, there is a certain amount of initial trial and error when working with ro or ro/di. Even if you do not add anything additional to the ro or tank water, things in a tank can affect the levels or stability of parameters between water changes. In my tank I batch 5.5 - 5.8 pH water. Between water changes the tank pH will drift upwards towards 6.5 and the new water is set to drop it back to about 6.0. (Inititially, I ran this tank at pH 4.2 and TDS of about 30 ppm.)

Whichever route you go, be sure to look around and compare units and prices. The one place I would suggest you do not shop is most online aquarium stores. You will pay more for no reason other than it is labelled for aquarium use.

[smitty]

Did some reading after my post and it seems that what I thought was wrong. Reverse Osmosis does not remove oxygen from R/O water. Never stop reading, and verify what you been taught is a good rule to live by.

[Viktor Jarikov]

I am on well water and run everything, both home and business water, through an RO. My system has the capacity to produce 10,000+ GPD of RO water of which I have been using 3,000-6000 daily for the past 4 years (continuous 24/7 water change in all my tanks and ponds).

So the sequence is:

well (~1500 ppm TDS (low end brackish), ~600 ppm out of the TDS is hardness, rest must be salinity, 1/4-1/2 ppm ammonia, tannin (yellow), sulfites (strong sulfur smell)) -->
sediment filter -->
RO membranes (~30 ppm TDS) -->
charcoal + calcite filter (calcite must have been spent a long time ago though) -->
another charcoal filter -->
added directly into four sumps for my 12 tanks (110 ppm TDS, 1-2 drops KH, same GH).

Altogether ~10-15 five-gal pails of seashells (thank you Naples beaches) are added to the sumps to gain a bit a hardness and minerals back (TDS raised to ~150 ppm, 2-3 drops KH, 4-5 drops GH), otherwise the water is way too soft for the vast majority of fish.

We drink the same water and use it for everything in the house - 110 ppm TDS, 1-2 drops KH, same GH (of course not out of the sumps but split off before).