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R/O system with permeate pump

raymond82

Member
Messages
345
Location
Amsterdam
Hi all,

While reading more and more in this forum I get the impression that for successful Apistogramma breeding I will need to buy an R/O unit. I'm using rainwater now but even in Holland I cannot get (but mostly store) enough to do biweekly water changes in three aquariums.

The only reason not to buy an R/O unit is that I think it will break my heart to see 3 liters of water wasted to produce 1 liter of osmosis water. Just now, I read something online about the Aquatec Permeate Pump. It supposedly reduces waste water with up to 80%. Does anyone have any experience with this?

Thanks!
 

tjudy

Moderator
Staff member
5 Year Member
Messages
2,822
Location
Stoughton, WI
A permeate pump is only suggested if your water pressure is less than 60 psi. As pressure to the RO membrane goes down, the ratio of waster:ro water goes up. A permeate pump does not really reduce the amount of waste water... it brings the level of waste down to the 3-4:1 ratio it should be. A ratio of less than 3:1 is not good for the life of the RO membrane.
 

raymond82

Member
Messages
345
Location
Amsterdam
Thank you for your reply!

I'm not sure what pressure is we get here but it would be helpful if the pressure is too low. In case we do get an R/O unit. I'm reading about ion exchangers now, from what I read they produce water with low conductivity but I thought the ppm is still high in this water, cause it exchanges Ca and Mg ions for Na ions. Would it still be useful for breeding apistogramma's?
 

jaafaman

Member
Messages
40
Location
Chattanooga, Tennessee
The all-house type of DI often does use potassium or sodium chloride for the exchange medium, but the types normally available through the hobby tend to use proper materials. API's model, for example, uses a mix of cationic/anionic resins within its column, which will exchange hydrogen and hydroxides for the undesirable ions in hard water. But they're usually also meant to be used until exhausted and then replaced, and although it's a bit difficult to do I have bought two of them before, seperated out the two resins and then used each as an individual stage so each could be recharged as necessary.

You could try a Brita filter before investing in the full setup if you choose to test out DI on your local water. They're about the oldest out there for personal water filters, and is still about the least expensive, but it does have a mixed-bed resin chamber as well as a charcoal pre-filter. I've used them to double filter water before in a pinch, and was able to get the Alabama water where I lived at the time (at about 120 ppm) down to as low as 20 microsiemens' conductivity. And I still keep a few around the house for the smaller tanks.

But Brita, moving to Pur and then Zero Water tends to increase the cost significantly. Good for a test and drinking water, but for an investment it'd be worth the time to investigate the rechargeable types...
 

wethumbs

Active Member
5 Year Member
Messages
476
A permeate pump is only rated for so many cycles. If one want to improve the RO rejection rate, you can connect several RO units in series. Such that the waste water from the 1st one unit goes into the input of the 2nd RO unit, so on and so forth. I had done this years ago with two RO units and the water that came out of the 2nd unit was just as good as the 1st one.

You can also add a membrane flush kit and do weekly flushing of the membrane to maintain its efficiency.

Here is what I am currently using.

IMG_3501.jpg
 

Mike Wise

Moderator
Staff member
5 Year Member
Messages
11,202
Location
Denver, Colorado, U.S.A.
The DI units that jaafaman refers to (exchange of H+ & OH-) can be recharged in theory. It requires the use of a strong acid (usually hydrochloric acid) and a strong base (usually caustic soda aka sodium hydroxide). Both are very dangerous to use - to you and your plumbing - if you don't know what you are doing. This is why you don't see companies that make these DI systems providing recharge products. The legal liabilities are just too great.
 

raymond82

Member
Messages
345
Location
Amsterdam
Thanks for all your replies! I will be digging into the prices of DI units, so far I had a little difficulty finding out which ones exchange H+ and OH-. The API one, for instance, I haven't been able to find yet but I'll do a bit more searching this weekend. Soon as I find out more I can also check how much replacement cartridges cost, if it's not too much I wouldn't have to recharge and put my life and plumbing at risk. In the end I will be balancing my reluctance to waste water to the size of my wallet...

Before trying a Brita (like) filter I will also try to read some reviews on them, in the end we have quite a lot of aquariums around so I'm not sure if they'll produce enough.

Two R/O units in series could also be an option, the cheapest R/O unit I found was only 30 euro (~37 dollars) and I read some pretty good reviews on it.

I get the impression that not many people use DI units, most people go for R/O units. Is this because of the hassle (or costs) of recharging it, or because the water doesn't reach required standards?
 

CopabX

Member
Messages
72
Location
NJ, US
A ratio of less than 3:1 is not good for the life of the RO membrane.


It is possible to be more efficient. My system has a ratio of 2:1. More stages are needed so that the membranes don't rupture but it is definitely possible to have lower waste. Also raymond, I wouldn't cheap out on the membranes and setup because it causes so much more hassle later and it may produce drinkable water, but not always below 50ppm.

http://farm8.staticflickr.com/7024/6691533917_a9352d0d13_b.jpg
"My Setup"

http://www.flickr.com/photos/71220625@N02/6691534501/in/photostream/
"Perm Pump"
 

jaafaman

Member
Messages
40
Location
Chattanooga, Tennessee
...Before trying a Brita (like) filter I will also try to read some reviews on them, in the end we have quite a lot of aquariums around so I'm not sure if they'll produce enough...
That was meant as a suggestion to test the efficacy of DI on your local water, not necessarily as your primary means of provision. The average on a Brita filter w/o overtaxing it at any given time is about 2 gal/day, which might help on a single 29-gallon or so but not much else.

...I get the impression that not many people use DI units, most people go for R/O units. Is this because of the hassle (or costs) of recharging it, or because the water doesn't reach required standards?
You get much, much more for your money as well as far less hassle with an RO unit...
 

raymond82

Member
Messages
345
Location
Amsterdam
Jaafaman, does that mean that the effectiveness of a Brita filter is a good predictor of the effectiveness of a proper DI unit, given the properties of my tap water? I thought DI units, especially the ones that exchange H+ and OH- would be more effective than the Brita filter. But your point about the amount it produces is important, it wouldn't be enough for all the aquariums.

Anyway, I have to say that I'm more tempted now to go for osmosis. CopabX, I would be interested to know in detail what it is you do to get your wastewater down, 2:1 already sounds more appealing than 3-4:1. Your picture looks pretty complicated, and I couldn't figure out where the trick is.

I was also wondering how you can get enough pressure in the second osmosis apparatus if you would connect two in line, as wethumbs suggested.

In the end, if I can get my wastewater as low as possible I think I'll go for osmosis in the future and use it whenever there's too little rainwater. If I would still feel bad about wasting water, I guess I have no other option than to set up a fairly-sized Tanganyika aquarium to give the wastewater a proper destination...
 

wethumbs

Active Member
5 Year Member
Messages
476
Copabx basically has a 3-stage prefilters (below the RO unit), couple with 2 resin filters and a post filter. There is a inline dual TDS meter connecting at the supply and the output of the RO/DI unit. The permeate pump helps to reduce waste water since it has a small pressurized tank as storage. I think 2:1 rejection rate for this setup is a bit optimistic even with a flow restrictor at the waste line.

One can tell a rupture membrane by the quality of the RO water. In most circumstances, the membrane will not be easily rupture. The reason why an 'old' RO unit losses its efficiency is due to clogging of the membrane. Large particles that could not pass through the membrane can get 'stuck' on the membrane and reduce its overall area for water to pass through. That's why a flush kit is useful in flush the membrane surface to dislodge these large particles and maintain the efficiency of the membrane.

There are couple of other ways to improve RO efficiency, one is to have higher water pressure (my water is at 80psi). The other is a higher supply water temperature. The higher supply water temperature has a drawback of increase bacteria growth which means more frequent filter change. To get higher water pressure, you will need a booster pump which is fairly expensive (cost more than a RO/DI unit). I had increased the supply water temperature to over 80F before and the efficiency of the RO unit was significantly improved.
 

CopabX

Member
Messages
72
Location
NJ, US
There is actually only one resin filter. The others are UV and taste filters. I pretty much get the 2:1 ratio because of how many prefilters there are in the setup. I also forgot to mention that my house has a couple more prefilters for incoming tap water so there is much less to filter out by the time it gets to the RO. Therefore I can get away with a higher pressure system than normal to decrease waste without clogging/bursting of the membranes (although I have done that and my ice was salty for weeks).
 

jaafaman

Member
Messages
40
Location
Chattanooga, Tennessee
On the subject of "waste water" from your Apistogramma RO, I'd like to drop a few names if I may:

Neolamprologus multifaciatus
Neolamprologus brevis
Neolamprologus similis

Julidochromis ornatus
Julidochromus marlieri
Julidochromus dickfeldi

Neolamprologus leleupi

Pick one name from the first group and multiply by seven.

Pick one name from the second group and multiply by five.

Pick just one of that third, solo group.

Mix with rock, sand and water in a suitably-located 38-gallon glass-walled box and call it a piece of Lake Tanganyika...
 

raymond82

Member
Messages
345
Location
Amsterdam
There is actually only one resin filter.

If I understand it correctly, a resin filter is an ion exchanger? Do I have to see this as having a DI unit in front of the RO? Isn't it possible to then just use the DI water? But this is an interesting solution, with just one resin filter in front. I was already reasoning that the purer the water is that you feed the RO, the less waste I will have. Although I have to say that we don't have any other filtration here in the house and the tap water comes quite hard (220 ppm).

Jaafaman, that is of course a wonderful solution. I have to admit that I was close to buying a 42 or 52 gallon aquarium not so long ago to make it a piece of Lake Tanganyika, I love these fish you mention. But since we're running close to 20 aquariums now (a collection we've build up in very little time) I wanted to slow down a bit. Or at least try... And, more importantly, I would really like to see Apistogramma fry so I want to devote all my attention to this first.
 

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