[andyM]

Should booster pump go before pre-filters or after on 4040 ro?
Does it even matter?
I've got 40 psi tap pressure and need to get it to 100 psi ideally at membrane for HF-4 membrane.
On my 400 gpd ro the pump is after pre-filters.

[Ian101]

ive had mine before prefilters for 3 years which i thought was correct position but some say it should be after the prefilters ?

[CleanClear]

Mine is before the prefilters, for ease really. I don't believe it matters at all.

[stu_thomson]

Mines before pre filters and one of the best things I've bought!

[andyM]

That's interesting thanks for your replies.
I've set mine up after pre-filters and seems to be working ok.
Although I might play around and try it before pre-filters to see if it makes any difference. 
Im happy with the performance of the 4040 with the booster pump (Clarke cbm240e) as production is much much faster than my old 400 gpd ro. 
The only slight problem I was having when setting up was that if I closed the waste valve too much it blew the inlet hozelock connector off of the pre-filter.
I presume this was due to too much back pressure?