Reducing RO membranes

[wildlifewarrior]

Hi Everyone,
So I made an RO system this year and was thinking about next year already. I know most of you guys use 150gpd membranes and have 4 or so in series, and are worried about sufficient flow over the last membrane or so. While I was watching my system run, I was wondering couldn't you run several 150 gpd membranes and then one or two 100gpd membranes? Would it not really matter?

Mike

[hodorskib]

The past two years I had 100gpd membranes and this year I upgrade to 150s and I have noticed about a 30% increase in rate of process and about 1.5% higher concentrate. I understand what you are thinking but I would lean towards keeping the surface area of the 150s especially as you get around 8% concentrate. I have not had them foul once even after processing 120+ gallons at a time.

[arcticair]

I am in the process of making the RO syatem , i know i need a 5 micron prefilter but what type of filter is used in the 3 other housings ? Any help would be greatly appreciated .

[wildlifewarrior]

You would use a 100 or 150 (as suggested by hodorskib, I am probably changing over next year) residential reverse osmosis membranes. There are a few discussions about building homemade ROs with parts list. Hordorskib has a good build along on his website you can follow.
Mike

[mff]

I'm on my third night of using the hodorskib design RO. I used three of the 150's. I had also considered the question by the OP, as well as two serial pump and membrane lines feeding merging into a single line.

Still much too little experience to offer any suggestions, but am very happy with the outcome so far, and many thanks, hodorskib, for sharing what you have.

I would note to others that you can (as I did) easily spend quite a lot on the incidentals - fittings, primarily, from the local hardware store. It was my first experience with the slip-joints and tubing, and was worth spending a little extra locally to ensure I got it right the first time, but it did add to the cost.