Retirement and forum shutdown (17 Jan 2022)

Hi,

John Howell who has managed the forum for years is getting on and wishes to retire from the role of managing it.
Over the years, he has managed the forum through good days and bad days and he has always been fair.
He has managed to bring his passion for fish keeping to the forum and keep it going for so long.

I wish to thank John for his hard work in keeping the forum going.

With John wishing to "retire" from the role of managing the forum and the forum receiving very little traffic, I think we must agree that forum has come to a natural conclusion and it's time to put it to rest.

I am proposing that the forum be made read-only from March 2022 onwards and that no new users or content be created. The website is still registered for several more years, so the content will still be accessible but no new topics or replies will be allowed.

If there is interest from the ITFS or other fish keeping clubs, we may redirect traffic to them or to a Facebook group but will not actively manage it.

I'd like to thank everyone over the years who helped with forum, posted a reply, started a new topic, ask a question and helped a newbie in fish keeping. And thank you to the sponsors who helped us along the away. Hopefully it made the hobby stronger.

I'd especially like to thank John Howell and Valerie Rousseau for all of their contributions, without them the forum would have never been has successful.

Thank you
Darragh Sherwin

Reverse Osmosis Unit

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Yasser (Sarah Cullen)
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20 Jul 2008 15:02 #1 by Yasser (Sarah Cullen)

Reverse Osmosis Unit was created by Yasser (Sarah Cullen)

I'm looking for a bit of advice on RO units. I'm in the process of setting up a 450 litre tank for marines. I've seen a few units but the smallest one I've seen produces 35 gallons a day. Thats a lot more than I need.

Is it true that the unit must be left on all the time? so a lot of the water will be going back down the drain.

What sort of life span do you get out of the filters on the units? Do they need changing every so often?

I used to use the API tap water purifier which didn't waste any water but I thought the cost of the refill cartridges was quite expensive in the long run.

I will be buying a RO unit, so can someone recommend a unit for me or possibly an alternative to RO.

Thank you.

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20 Jul 2008 16:35 - 20 Jul 2008 16:36 #2 by adamireland (Adam Jackson)

Replied by adamireland (Adam Jackson) on topic Re:Reverse Osmosis Unit

I havent seen any of the RO units produce what they say on the box (water pressure) unless its a Kuna water RO

you dont need to have it running 24/7 just run it for how much water you need... for the amount of water you need, i wouldnt worry about which one you get.. DD do a nice one but you can buy them for as little as 70 -80 euro on the net.

membranes last for about a year on good use. sediment and carbon tend not to last more than 6 months. turning brown

to reduce the amount of waste water, you can stack the membranes. a total of 3 on a stack will reduce the waste down to a minimum. anything more than 3 and your wasting your time..

HMA filters are a close comparison and produce similar water, though not as good as RO.

HTH

Adam

Last edit: 20 Jul 2008 16:36 by adamireland (Adam Jackson).

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20 Jul 2008 16:39 - 20 Jul 2008 16:41 #3 by Daragh_Owens (Daragh Owens)

Replied by Daragh_Owens (Daragh Owens) on topic Re:Reverse Osmosis Unit

I don't know a lot about RO units, I have only recently purchased and started using one. Mine is a 250 GPD unit and it barely trickles out.

The rating on RO units is based on maximum possible performance, typically in the small print you will see something like:

Production Rate Based on: TDS 450 PPM, Water Pressure 65 PSI & Water Temperature 25-C.

I don't know what your TDS is like but most users are unlikely to have 65 PSI pressure and are never going to be runnign in water at 25C!

Also the gallons referred to are US gallons not imperial gallons, which are slightly less than imperial. So realistically you may get 10 regular gallons of RO water from a 24 hour stretch from the unit you mention.

Finally, no you don't have to leave them on all the time, but once you wet the membranes you must keep them wet. Don't let them dry out. That is no problem when you turn off the water supply, the water in the unit will keep the membranes wet.

Last edit: 20 Jul 2008 16:41 by Daragh_Owens (Daragh Owens).

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20 Jul 2008 16:39 #4 by Daragh_Owens (Daragh Owens)

Replied by Daragh_Owens (Daragh Owens) on topic Re:Reverse Osmosis Unit

Adam, you type faster than I do :-)

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JohnH (John)
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20 Jul 2008 16:50 #5 by JohnH (John)

Replied by JohnH (John) on topic Re:Reverse Osmosis Unit

Hello;
This will not be a definitive reply - just one based on my experiences with R/Os now and a few years back.

Doubtless someone with more technical knowledge on the subject will come along presently but in the meantime here are my experiences.

When I had my first R/O unit in England about eight or nine years ago the perceived thinking then was that it had to be 'under pressure' at all times for fear the membrane would become contaminated with bacteria and start to let water past the membrane but now that principle seems less neccessary, whether because the membranes are now 'tougher' or not, I wouldn't like to say, but it doesn't seem essential now.

Most modern R/O units now come equipped with a pressure meter which tell you the pressure of water passing over the membrane, when the pressure drops appreciably it's time to change the pre-filters but generally it is suggested you change them every six months anyway.
Another 'boon' on modern ones is the 'reverse flush' mode, this pushes water under pressure against the membrane in the opposite direction to the general flow and 'flushes' away many of the contaminants from it, resulting in a longer membrane life.

As to the output level, this is actually in US gallons, so production is of rather less than that quoted.

My suggestion would be to check with the nearest Forum Sponsor to you to see if they supply them (always better if spares or help are/is needed) but if not there's always good old ebay...but let buyer beware here, you really can't be certain what you end up with and it could be a long way to return a faulty one.
The R/O unit I have now is an RO-Man unit, bought on a trip back to England last year. I can certainly recommend this type, although it's still a long way away for spares etc.

I do have to stress that mine is only for making my 'well' water habitable to soft-water fish, I have absolutley no knowledge of Marine use.

Hope this helps a little until a Marine person can help you further.

John

Location:
N. Tipp

We're just two lost souls swimming in a fish bowl - year after year.

ITFS member.

It's a long way to Tipperary.

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20 Jul 2008 16:55 #6 by Daragh_Owens (Daragh Owens)

Replied by Daragh_Owens (Daragh Owens) on topic Re:Reverse Osmosis Unit

Guess broadband has not made it over the Slieve Bloom mountains yet ;-)

Yasser think you have a record, three people reply to one query at the same time. Luckily we are all agreeing, it would have been great fin if you got three different answers :-)

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JohnH (John)
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20 Jul 2008 16:55 #7 by JohnH (John)

Replied by JohnH (John) on topic Re:Reverse Osmosis Unit

Adam, you type faster than I do

...and I type slowest of all !!!

John

Location:
N. Tipp

We're just two lost souls swimming in a fish bowl - year after year.

ITFS member.

It's a long way to Tipperary.

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Yasser (Sarah Cullen)
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20 Jul 2008 18:09 #8 by Yasser (Sarah Cullen)

Replied by Yasser (Sarah Cullen) on topic Re:Reverse Osmosis Unit

Thanks for the replys guys, so what size unit should I get for my tank. It's 468 litres (when empty).

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20 Jul 2008 19:01 #9 by adamireland (Adam Jackson)

Replied by adamireland (Adam Jackson) on topic Re:Reverse Osmosis Unit

arent marine tanks just tropical tanks with a bit of tesco's salt added?

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20 Jul 2008 23:18 #10 by Daragh_Owens (Daragh Owens)

Replied by Daragh_Owens (Daragh Owens) on topic Re:Reverse Osmosis Unit

adamireland wrote:

arent marine tanks just tropical tanks with a bit of tesco's salt added?

I think so.

As to the size unit you require Yasser, the one you mentioned should provide enough RO water for regular water changes. Even it it only produces 10 gallons a day thats over 60% of the tank volume in a week.

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Retirement and forum shutdown (17 Jan 2022)

Reverse Osmosis Unit