help with RODI system.

[cst0215]

Hello all.

I am stumped with my BRS 4 stage 75gpd system.

I am getting very high tds readings after the water leaves the membrane.water

I have isolated the plumbing so that the unfiltered water goes into my sediment filter, than the carbon filter, then directly into the RO membrane and then to the drain line and final water collection bucket (bypassing the DI filter completely).

I have plumbed my dual sensor TDS meter so that it is reading the water directly as it enters the RO membrane housing and leaves the RO housing.

I was already getting high rejection rate, so I have installed a new membrane rated at 75 gallons per day and as far as I can tell, the membrane is fully seated in the housing with the stem even with the top of the housing threads.

Even with the new membrane I am getting readings of 358 incoming and 127 outgoing. This is a rejection rate of 64%

I have a flush valve installed on the waste line that has 550 marked on the side.

This is a used system that sat for approx 6 weeks before I recently started getting it installed. I was told that all of the filters were recently replaced before I got the system and the sediment filter is completely white.

Any help and advice would be greatly appreciated

 

[Asm481]

Are you giving it a good 10-15 minute run before judging the tds? Most times the meter is after the membrane and after di canister. Hope it works out for you.

 

[chrizo]

Isn't the tds meter supposed to be after the membrane and the last one after the DI stage?

 

[Hammy]

64% rejection is definitely way too low, especially with a new membrane. Since you already changed the membrane and checked that it’s seated correctly, I’d check the waste-to-product water ratio and the pressure going into the membrane next. Also make sure the flow restrictor actually matches the 75 GPD membrane. If pressure and waste ratio are good but you’re still seeing 127 TDS after the membrane, I’d start looking at the membrane housing or seals/O-rings for bypass

 

[UncommonSense]

Along with the good advice above, I’m curious about the RO membrane itself!

Is this a direct factory replacement Dow Filmtec 75GPD membrane?