Reverse Osmosis worth the effort?

[Cydone]

Hi all,

I have an 800l "North West" Amazon biotope setup with the following stock:
4 L075
4 L091
4 L201
20 C. Duplicareus (Never had any eggs, for at least 12 months)
200 Cardinals

Fish are doing well. But about 1 month ago I got 3 more C. duplicareus, and in at the same time I was trying to mix my water with rainwater over the course of 8 water changes. Sometimes i didnt get enough rain, sometimes it was rather dirty. The 3 new (i hope) C. Duplicareus died in the span of 3 weeks. The only reason I can find is the change in water parameters (or dirty rainwater), that affected the newcomers, more than the old stock.

We have pretty hard water here in southern Denmark, thus I have been trying for a year to get a good rain water collection system going. It is not working well/unstable. (I am therefore considering getting an RO system)

Current water parameters:
26c
PH 7.6-8
GH 21+
KH 15+
PPM/uS 300+/600+

Nitrates, Nitrite and ammonium are all 0.

Will my fish benefit from a slow move towards a Reverse Osmosis/Tap water mix? If so, what GH/KH/PPM should I aim for?

Or rather, is it not worth the effort?

Kind regards
Thomas

[MarcW]

The main reason I use reverse osmosis is that my tap water has 40 + ppm of nitrate, but in all other parameters seems to be very similar to yours.

I think that your water should be ok for keeping the fish, I kept mine in local tap water for 3-4 years, including some wild caught L128 & L134, they seemed to do fine.

I feel like I should be trying to replicate their natural environment as closely as reasonably possible, which is why I now use RO, I mix in a bit of tap water to buffer things, about 90% RO to 10% tap. That seems a reasonable compromise for me.

I'm not sure that rain water would have killed you new fish, but it may have been the final straw, if they had already been stressed, or overly medicated before you acquired them.

It would be worth keeping new fish in a quarantine tank, for at least a month to monitor them, if at all possible.

[TwoTankAmin]

I use an RO/DI unit. This will output water that shows as 0 TDS. Without the DI part, I cannot get to 0. De-ionization is the most effective non-biological method for dealing with nitrate in some aquaria, imo. Unlike the posters above, my water is not hard at all. pH 7.0, TDS- High = 83 ppm. Low = 55 ppm after big rains). I mostly use the unit for an altum angel tank. I am trying to target pH 6.0 and to keep the TDS in the 50 to 60 ppm range. Between water changes the TDS tend to rise about 10 ppm and the pH moves towards 6.5. I do occasionally use my RO/DI water to help when beginning the start of a rainy season changeover.

I find the biggest difficulty is stability of the parameters. I stain the water with a mix of botanicals some of which help to soften the water while others do the reverse. I spend a half hour or more batching the changing water which is about a 50/50 mix with my tap. None of this is possible without accurate monitoring of parameters. For this I use a continuous monitor which shows pH, TDS (or conductivity) and temperature. When I batch changing water in a big container by the tank, I can move the probes from the tank to the container.

My personal experience has been that when one keeps many of the SA soft water catfish, they may do OK in harder water, but either they may not spawn or, if they do, the eggs don't hatch out fry.

[Shane]

Thomas,
I have owned and used many RO units over the years. They are useful for carefully controlling the parameters in a small breeding or species tank. Much less useful for week to week water changes if you have a very large tank or even a fish room.

Your tank is about 211 gallons and I think that the ideal water parameters you would want would require about 75% RO. Keep in mind that just to do your weekly water change you will need about 75 gallons of RO in some sort of storage.

RO units waste about 10 gallons of water for every 1 gallon of RO they produce. So, you will be dumping about 750 gallons of tap water down your waste drain every week (11,350 liters per month). If you pay for water that can get expensive.

You will also need to find a 100 gallon storage tank and have it installed near the RO unit. Depending on the RO unit, it may take several days to fill the storage tank. Once filled you can add tap water, test the parameters, and then do a water change.

As you can see, all of this is not realistic for an average fish keeper for weekly maintenance of large tanks or many tanks.
-Shane

[PseudaSmart]

Using RO Water

Shane’s post is so last century I thought I’d give a more modern description of using RO Water.

My fish room at its peak had over 2500 gallons of water in aquariums and filter systems. Aquariums were 180 In addition I could hold 300 gal of water for WCs. All tanks had overflows and drip nozzles for an automatic water change system. My well water is liquid rock so RO was the most realistic option. Needing a lot of water and being an engineer I have done a bit of customizing. With this setup the membranes last about a year before needing replacement.

My system
Produces about 320 gal per day with about 420 gal waste water. Total from well about 750 gal working out to a ratio just over 1:1.3 (Typical modern systems have a ratio of 1:2 or 1:3). Particle and carbon filters, 4 90 gpd RO membranes, 2 booster pumps, float switch, 4 sprinkler valves, and adjustable flow restrictors.
After a bank of Particle and carbon filters the water is split into two parallel RO systems. Each has a booster pump to increase the water pressure to 85 ps before going into the first of two 90 gpd RO membranes. The pure water out is connected to a line running into a storage tank. The waste line goes into the second RO membrane. The pure water line is connected to the same line as the first. The waste line first goes thru an adjustable flow restrictor and then to a house drain.
I hope you can follow

Comments
The higher line pressure from the booster pump increases the efficiency of the membranes.
By using the waste water from the first membrane as the supply for the second the efficiency is almost doubled.
The pressure of waste water from the first RO membrane is too low for the second RO membrane to work. The adjustable flow restrictor on the waste line of the second membrane are necessary to provide enough back pressure for the membrane to work without trashing the membranes.
Disclaimer- anyone who has tried to double up a system failed to properly adjust the back pressure and is about to write post that it can’t be done. If interested I can describe in another post how it’s done.
The sprinkler valves are used on the supply line, common waste line, and common RO line. When the system is off these valves close keeping the membranes wet and under pressure. Otherwise they dry out and are less efficient until saturated. I believe it also reduces bacteria and fungus growth.

Adjusting water parameters
All storage tubs have air stones, helps mix water and stabilize ph.
I only do 2 different mixes one for breeding and one for grow out.
Since the tub drains down to the same level every time I know how much “stuff” has to be added for each new tub. I use a conductivity meter when done just to verify. When everything is ready I press a button and the automatic water change takes over.

I have been asked a few times about my setup so this is my first draft. I hope it helps a bit and I welcome comments for improvements.

Jim

[Bas Pels]

With regard to the setup. I do think I understand what you are doing.

You start with tap water @ say 50 units of dissolved matter, make RO water out of it, and get waste water of around 70 units of dissolved matter.

This goes through a pump, and through a second RO unit making more RO water, and waste water of arond 90 units.

Now what I wonder is, a pump will - as far as I know - never produce a stable pressure. I think an unstable pressure will harm the RO membrane, so how did you manage to get the pressure even, stable?

[Cydone]

That's a setup I would love to try when I get another house. It sounds great.

The research I have done mimics what you say Pseuda, I have found 3 units that will all produce "reasonable" amounts of waste water. (Depending on temperature/pressure)
500GPD 1:1
600GPD 1:2
800GDP 1:3

As an avid gardener I can use the wastewater there, at least in the warmer months.

I want a high GDP system that won't have to shot down to cool off, so that I can do w/c directly, and avoid storage.

In effect my concern is not so much the hassle. (I have tried with very intricate rainwater systems for a year, and its been very time consuming. I can't collect directly from my thatched roof)

My concern is whether my fish will benefit at all. If they don't care, why bother.

I am however, like Marc, trying to mimic the habitats of my fish as much as possible, down to getting leaves/debris from the amazon. Better water parameters would be a natural next step.

Thanks for your feedback!

[stuby]

It all depends on what you want out of your fish..... if you are just looking to keep some nice fish in a tank than you can get away without a RO filter. If you want them to breed and I feel do better than a RO filter is the way to go. My water is around 275ppm to 300ppm TDS..... I take it down to 150ppm to 120ppm depending on what I am trying to do. I change out between 100 to 190 gallons of water per day (I have 70 tanks set up) so I make about 50 to 100 gallons of RO water per day..... I have a RO filter that is capable of making ~700 gallons per day. You wouldn't need a big RO filter and you could still collect rain water and just use RO to substitute what you lack in rain water. To me the trouble and cost is worth it..... but the question should be is it worth it to you.

HTH
Chuck

[PseudaSmart]

Good questions!
Stable pressure using Booster pumps
This took a while to figure out. The pumps have an over pressure bypass built-in allowing the pumps to run continuously instead of quickly cycling off/onbut they still sound rough. The problem is the diameter of the tubing that comes with the RO system. Imagine trying to suck all that water thru a tiny straw. There is too much restriction so I replaced all supply tubing from ¼” to 3/8”. The tubing after the first membrane did not change. The change was obvious with improved flow and the pumps were much quieter.


Fresh RO water directly into aquarium
NOT RECOMMENDED. Potentially deadly depending on volume added. Aged RO water is okay.
A forum search should turn up a wealth of information on the topic.

Is it worth the effort and cost?
DEFINITELY! Soft water fish look far better and are healthier in the proper water conditions. I am certain that without RO water many fish could not have been spawned in aquaria and others with far more difficulty.
I like using only RO water because it removes and variation or oddball events in a public water system.
Jim

[Bas Pels]

Personally I would suggest using the waste water for a tank of Central Americal cichlids.

These look better in harder water, and are rather sensitive for old, polluted water. Having say 200 liter a week to dispose of, you could easily flow this through a 1000 liter tank.

Alternatively, if you don't like these cichlids, all kinds of molllies and sworttails come from the same water. And a tank with a hundred mollies or sworttails is quite spectacular. As they come from the same water, their weater preverence is the same.

However, this is assuming your tap water is rather free of nitrates - 10 mg/l will increase to 20 mg/l, which is at the top of what you would want to use

[MichaelItelf]

Thanks everyone for the advice, Ill give it a go Hopefully itss not too scratchy for the chooks. Is it better then hay in regards to mites living in it?

[Cydone]

Couldn't you mix say 75% RO with 25% Tap water, in a "mixer" of sorts on top of the tank, that then drips directly into the aquarium?

[PseudaSmart]

Cydone,
You are thinking in the right direction. Just be sure to test the water before it goes into the tank until you are confident it works.
Jim

[Cydone]

I made the plunge, and bought a 600GPD RO unit, and I have everything set up now. After getting over the initial fear that the unit might explode into my face after potentially failing the setup, it now works smoothly

I'm not here to chase numbers too much though, I just want more suitable water for my L numbers.

My plan is to bring my tap water down from a TDS of 350ppm to a TDS mix of 150ppm. But would a TDS of say 100ppm be better, in general, for most L numbers? I know that might sound a bit vague, given the variance of Amazon waters. But gun to the head, what TDS value would YOU come up with?

Cheers
Thomas

[MarcW]

I started by mixing 50:50 tap and RO, my tap is around 350ppm too. Over time I've gradually added more RO, now I do about 10% tap (filtered through a sediment filter and two carbon cartridges to remove chlorine and heavy metals) to 90% RO, this gives me a product of around 60 ppm TDS.

The move to more RO is mainly down to the high levels of Nitrate in my tap water, its around 40ppm right out of the tap.

I need to get around to testing the pH of the water, the fish seem happy though! I only have a liquid dropper pH test which doesn't seem to give good results, hopefully soon I'll get a pen or constant monitor when I figure out which one is good for a reasonable price!

[svelekei]

I just switched to all RO and I remineralize. I live in the city (Orange County CA) and my water is unpredictable crap, which out of the blue killed 4 L450’s and 1 L236 (my prized possessions at the moment). Luckily I still have 4 L236 and 1 450 left. Moral of the story is, I was cutting my RO with my tap like you and the unpredictabile happened. Everything was rolling along great until to my horror my fish started dying. I realized after the fact, there was a huge smell of chlorine I hadn’t smelled before and my tds from my tap changed by 150 points. I was also dechlorinating but still didn’t make a difference. I don’t take any chances now.