RO/DI pressure drop after changing membrane

[Ligershark]

So today I changed all my ro filters and my membrane. The membrane was a little over 2 years old and I wanted to up the per day amount anyways so I figured what the heck.

I went from a 50 gpd membrane to a 75 gpd membrane. My old flow restrictor was a capillary restrictor. The new one I purchased from BRS is the 500ML unit which is not a capillary unit. This is the one BRS recommends for the 75 gpd membrane.

My pressure has dropped to 30psi from a psi of about 60-70 prior to changing the membrane and filters. What gives? Both membranes are filmtec.

I measured my waste water for 1 minute and the equation ends up with 140.6 gallons/day. My product water is 22.5 gallons/day. Waste to product ratio is 6.25:1 which isn't bad but I wanted 75 gpd output.

Im going to put the old membrane and restrictor on tomorrow morning and see what the pressure gauge reads. If I get a good pressure rating I'm going to order a 75gpd capillary restrictor and see where that takes me.

Do I need a booster pump or is something wrong? Is it normal for the pressure to decrease when going to a larger membrane?

 

[AZDesertRat]

One issue is you have too much going out the waste line. Try your old capillary tube restrictor with the new membrane and see if it is closer to 3:1 to 4:1 waste ratio.
When you waste too much you lose pressue out the waste line. I would return the fixed restrictor and buy a new untrimmed capillary tube the follow the directions on how to trim it for your exact conditions. I hate it when vendors talk people into fixed restrictors, rarely are they ever correct since everyones TDS, pressure and temperature are different.