Rverse Osmosis

[fkn001]

Hallo all, hope you got through Xmas without too much extra deadweight.....

I have been thinking about adding a RO system to my indoor growing-on/QT tank, and after lots of reading here and elsewhere, I now have a pretty good idea of the system I want. requirements were
- low, or no, power consumption
- low ratio of "waste" water, I can only water my garden so much, and pouring tap water into the drain does not bear thinking about......
- capacity of more than 1000 liters/day
- low, low cost........
- low maintenance cost (replacement part) with long service intervals.

I then came accross the GE Merlin Point-of-use system and this seems to fit the requirements and more. No power consumption, relatively low waste water ratio (app. 75 % or so, I am being told by dealers), high capacity of at least 2000 liter/day depending on tap pressure (I have app 45 Psi here), temperature and GH of tapwater, and it is easy too on the maintenance cost. It can be had for 265 £, and there is also a Flush Kit that can be fitted at extra cost. http://www.gewater.com/pdf/resdntl/home" onclick="window.open(this.href);return false; ... _Guide.pdf

of course, as the research went on, I came across an Article by Mike Snaden on the Yume Koi website, http://www.yumekoi.com/images/stories/p" onclick="window.open(this.href);return false; ... t_2003.pdf, and this of course led to a slight change of plan, so that I now want a secondary pump operated unit which is being fed the waste water from the first unit, thus reducing overall amount of waste water. Thought is I will let the waste water from the first unit run into a tank, and then run the pump on a float switch to the second unit. Of course, as with all my koi tinkering, cost has now gone up.........but that is as inevitable as the sun rises in the East and the She KS (Koi Stopper) paying close attention to any additional gadget costs.....

I am aware that the second unit may give less flow as it is being fed waste water from the first unit, but so be it. I will also install an in-line TDS meter so I can keep an eye on performance, as well as keeping track of TDS levels in the tank. Since the output of this Merlin is more than required, it will run on a timer.

My question is if anyone has any experience with the Merlin RO, or has other recommendations in line with above, whether for another unit or design/system layout in general.

/Flemming

[Gazza]

Hi,

Not an easy one to answer easily to be honest as there are many products out there on the market.You will probably find you will need to use a booster pump as otherwise you will not get a very good flow of product water and you will defiantly have waste.

I use Alan on the link bellow and find them very reasonable:

http://www.purewaterproducts.co.uk/index.php" onclick="window.open(this.href);return false;

[Davej]

Hi Flemming

I doubt you will get anywhere near 2000l a day from a Merlin unit at 45 PSI pressure, even at summer temps. Not sure that any of the Guys running RO over here are using Merlin units.

I use a 4040 unit with an Ultratec HF4 Membrane, at 50PSI it delivers 350 gpd at 10C input temp even with a 3 year old membrane. From what I understand the Ultratec HF5 Membrane will deliver a fair bit more.

You must have a fair size QT to need a unit of this size?

Dave

[John D]

I used a Merlin RO unit some 5 years ago when I had a play with RO and was not that impressed. I had good water pressure of ~ 50 psi and the waste water was ~ 70% and good only 30%. This was the main reason for me giving up on the RO thing as I was on a meter with a large pond.

I think there are better options available now.

[Dave Collins]

Merlin unit - don't touch it. I've got one sitting on a shelf. Waste water at 70 - 75% and the water meter trying to spin off its axe. It will give you 1,500 litres a day in summer and throw 6,000 litres down the drain.

I now have a 450litres a day unit from http://www.purewaterproducts.co.uk/index.php" onclick="window.open(this.href);return false; , have a chat with Alan. The unit comes coupled ready for Koi ponds, first unit waste feeds 2nd unit etc. At 60% good water/ 40% waste it actually produces 720 litres of good water a day with a TDS of 16. Still not cheap as with 480 litres going to waste then you're still using 1,200 litres of water a day.

rgds

Dave

[greg]

I changed over to RO water this year (April) and all the advice i received was to steer away from the Merlin unit as it is a bag of spanners and not fit for purpose.

Most of the serious hobbyists i know who need larger systems are using the:-

4040 unit with a HF membrane

OR

the Aqausoft Industrial unit.

Remember if your going to use one of the RO units that doesn't have built in pre-filtration YOU WILL NEED THIS aswell to remove the chlorine before entering the unit.

[fkn001]

Happy new year

thanks, Dave and Greg, for your replies, very valuable. I did think that the Merlin sounded a little too good to be true, and for some reason I can not begin to understand , the manufactures and all the sellers have forgotten to mention the waste water ratio. must be some very rare oversight on their part.......

I will look into the 4040 which sounds just like fitting requirements.

actually I have 2 Q/T's, one outside of 2800 Liter and another 1300 Liter heated inside which is used for growth whenever not used as a hospital (fortunately not very often). my thinking was that the RO system would supply both, however not running all the time, but something like 4-8 hours per day as required, and it could also be used, in it's spare time, to supply the main pond of 28,000 Liters. the tap water here has a KH of 16-17 Dh, or app 300 Mg/l, with the Ph then running at 8 -8,5, and this is a little too high for my liking. Regarding a prefilter, there is no Clorine or Cholaramines in the tap water, so I suppose I could live without it, but just to be on the safe side and to trap any fines, it will be there......

Thanks again for steering me clear of the Merlin.

/Flemming