[Mike55]

Hi guys

I am having trouble producing low tds water following replacement of my HF5 membrane.

I cannot get the pure tds below 46 from an input of 280.

Half inch fittings throughout, mebrane correct way round, both ends have o rings, no leaks, in PSI of 50.

Flushed for two hours and waste controlled with gate valve (which I've checked and is working).

Any suggestions as tearing my hair out here......could it be a dodgy membrane?

[martin hulstone]

Sounds like you need a pump to get your tds down.
Clarke 240 around 300 quid seems to be most popular

[Mike55]

I've ruled out being a pressure problem.  50psi with a HF5 should be bringing the tds down much lower than that.

I've tested the membrane in my friend's RO housing this evening.  His PSI in is 35 and was bringing my membrane tds down to 70.  We then put his membrane back in and it's bringing his down to 20 and his is over two years old.   Exact same membrane (Axeon HF5).

Looks like there's a problem with the membrane.  Anyone come across this it would be interesting to hear?

[Alex Gardiner]

I've ruled out being a pressure problem.  50psi with a HF5 should be bringing the tds down much lower than that.

I've tested the membrane in my friend's RO housing this evening.  His PSI in is 35 and was bringing my membrane tds down to 70.  We then put his membrane back in and it's bringing his down to 20 and his is over two years old.   Exact same membrane (Axeon HF5).

Looks like there's a problem with the membrane.  Anyone come across this it would be interesting to hear?

Although an HF5 membrane can work on these relatively low pressures it is not ideal for bedding them down.

I would advise a minimum of 24-48 hours of production before the new membrane will be anywhere near optimum production conditions.