[Simon Carter]

I bought a Merlin a while back, plus a supposedly appropriate pump, but gave up on it after about a week. Very poor production & diabolical waste ratio. I bought it as back up for by Omnipole RO. I still need that back up.
It's been suggested to me that a Merlin is sensitive, but a good piece of kit if 'doctored' by the right company & with the right pump.
I might try again with it, but I'm also concerned that the membranes have dried out. I'm told that's not good.

[welmac]

i run a merlin with my system and dont really have any complaints. it produces alot of pure water, and doesnt have a "bad" waste ratio: about 2 parts waste to 1 part pure. the only thing with the merlin is if you have a low tap pressure (probably anything less than 60psi) then you want get good results. im fortuanate that i have a pressure of 70psi. my water produced is about 13ppm (tap ppm is 190, hardwater).

out of the pumps that i have seen ones try to use to boost the pressure on the merlin, i have only found one that i think is a good pump............but it costs about £600  personally i think that if you have a low pressure you are better off purchasing a "smaller unit" that has a booster pump already fitted. although you may not produce as much water as a merlin, you will produce clean water consistantly.

Gary - WELMAC

[JM123]

we only have 48psi tap pressure here - tds of 300/350ppm and our merlin still produces 2000ltrs/day at 5ppm - try fitting a 10 or 20inch sediment filter and housing before the merlin, make sure there are no leaks - if that doesn't work then you haven't put your merlin together correctly, check the membranes and sed filter are correctly bedded in the sumps.

I set a merlin up for a customer with only 35 - 40psi pressure and tds of 485ppm!!  he gets 1400ltrs a day at 12ppm.

[freshwater]

The good old Merlin question again.

The Merlin was designed for domestic/light commercial ues and not for window cleaners. It has however been promoted as the best thing since sliced bread as far as window cleaners are concerned. In many cases this is true, but if you have low water pressure and a low temperature and the wrong sort of water its not the case. It should be realised (not that may do)that the production rate of all ROs is pressure, temperature & TDS dependant. Most ROs are tested at high pressure & high temperature (25'C) and with a special water that has be made up in the lab, if you run your RO close to these parameters then you will be OK, but once you move away your water quality & production rate will suffer.

As pressure drops your production rate will fall, bt more important your water quality will also fall.

As temperature falls from the 25'C down to the UKs more normal 5'C your production rate can fall by as much as 50%.

As the make up of your water moves away from the norm your water quality will fall off, more TDS getting through.

So ask around before you buy a Merlin, try to find someone in your area who has one and ask them the questions.

As far as pumps are concrened Gary from Welmac is quite right, you need a special pump which cost £600 (if you want one send us an e-mail), it will deliver a good flow rate at a high pressure. The one that is sold by GEwater to go with the Merlin (an Aquatec pump) is only for low demand use and will overheat if left running for any lengt of time. As Gary says if you have low pressure you are better off buying a smaller pumped unit like the ones on his web site.

Note on membranes. Membranes should be kept damp, once they dry out they can crack which will mean lower quality water. They are best left in the RO under pressure, fit valves on all your pipes. If you leave them damp but open to the air bacteria can get in and grow on them and agian your water quality will suffer. And last of all run them at leats once a week, this will flush the surface and remove anything that has settled on the surface and will also replace the water to eef them fresh and bacteria free.

[JM123]

firstly I agree with what freshwater says about temp/tds/pressure etc, but to be totally honest I can't recommend the merlin enough - thats not to say in certain areas eg Kent where tds levels can be sky high (600+) a merlin wouldn't be suitable,on the whole however I believe the merlin represents the best value for money system out there, other than a merlin I would go for an AquaFX unit (Great White 300GPD pumped 9 stage system)