Hi, looking for a update which booster pumps are people using with their merlin prf-ro, my pressure is 40psi at the moment. Could some body point me to posts about adding a prefilter before the carbon filter so it lasts longer as mine is only last 2 months and the total pure and waste is over the 38,000ltrs
What ever booster pump will work on a 4021 will work on a PRF.
I suggest you contact Daqua.co.uk and ask Doug the question. He lists a pump that will work for a 4021.
With regard to a prefilter, any prefilter housing will do. I would suggest a double prefilter, one for sediment and the other for a carbon block. My preference is 20" and a Fiberdyne carbon block.
Again, Doug will be able to sort this out for you.
I would also suggest you measure your waste to pure ratio. The early Merlins were very water wasteful having a 5 to 1 ratio. I believe the later PRF aren't as bad. I believe they are around 3 to 1.
Depending on your tap water tds you may be able to reduce that further. A 1/2" gate valve plumbed into the waste water pipe with relevant 1/2" fittings will help you throttle the waste back a bit more.