GAPS water.
Axeon HF5
IMHO this is the best one. Its not the cheapest but is far better quality overall than some of the cheap chinese counterfeits out there.
One of the lads from another forum was tempted by the price of this membrane.
http://www.windowcleaningwarehouse.co.uk/best-value-hf4-4040-membrane.htmlUnfortunately for him it did exactly what they said it would do - 80% rejection rate. The cost of resin to polish of the remaining tds will eventually be more than the saving on the membrane's purchase price.
We have a champ housing so these are the instructions for this model. It will be a similar procedure for any other housing.
You only need to remove the feed end housing to remove and replace the membrane.
Insert the membrane into the housing with the black brine seal at the feed end (ie feed the membrane in with
the brine seal end going in last). Always good to smear a very thin coat of silicone grease onto the o rings to help them slide in easier. (You can also use Vaseline. ) Push the membrane firmly to ensure it is fully inserted. Push in the end cap, again ensure it is fully inserted to reveal the holding ring groove (Champ housing). Replace the holding ring (Champ Housing.)