Technical questions about RODI filter

Bobbofin · 03/15/2015, 01:57 PM

Recently replaced the sediment, carbon block, membrane (2+ years old) and DI on my BRS 4 stage RODI. I usually change sediment, carbon block and DI every 3-4 months after a couple of hundred gallons of use to get TDS back down to zero. This time it was up around 12 TDS so I changed the membrane too. While I had the unit out from under my cabinet I installed a pressure gauge in between the carbon block and RO membrane. While the unit is running I get 60 psi. How much should I let the pressure drop before changing sediment, carbon block, and DI? Is 60 psi enough pressure to effectively run a 75 GPD RODI? Where my tap water is so bad (300-350 TDS) would I benefit from using 1 micron sediment and carbon block filters instead of 5 micron or would they just clog very quickly?

I seem to go through DI rather quickly because the TDS out of the tap is 300-350 and there's probably CO2 in the water. Where I live in a condo without a basement I really have no room to let water sit in a bucket so the CO2 will evaporate then have a pressure pump to the pump it through the RODI so just replacing the DI more often is my only option.

Next time I buy sediment, carbon block, and DI kit from BRS I'm going to pick up the inline TDS meter so I can test the TDS coming out of the membrane. I test the TDS of the water I use coming out of the DI for tank use with a hand held unit.

azjohnny · 03/15/2015, 03:19 PM

I would get a TDS meter and test your water at these points. feed, post membrane and post DI. You shouldn't have to replace the sediment and carbon filters so often if they are a quality filter. Use as small of a pore size as you can, they serve to protect the membrane. You might also want to go with a better membrane 12 ppm out of 350 is a poor ratio ( 96.4%) I have 99% with a Spectrapure Select Plus. I have 650 ppm and get 6 ppm post membrane.

I think your membrane has a lot to do with your problem. 60psi is ok, you would do better with more pressure

pore size on the sediment filters

sediment .2
carbon .5

the bigger the pore size the more they are letting through, the sediment and carbon do nothing to remove TDS

03/15/2015, 01:57 PM	#1
Bobbofin Registered Member Join Date: Jun 2009 Posts: 137	Technical questions about RODI filter Recently replaced the sediment, carbon block, membrane (2+ years old) and DI on my BRS 4 stage RODI. I usually change sediment, carbon block and DI every 3-4 months after a couple of hundred gallons of use to get TDS back down to zero. This time it was up around 12 TDS so I changed the membrane too. While I had the unit out from under my cabinet I installed a pressure gauge in between the carbon block and RO membrane. While the unit is running I get 60 psi. How much should I let the pressure drop before changing sediment, carbon block, and DI? Is 60 psi enough pressure to effectively run a 75 GPD RODI? Where my tap water is so bad (300-350 TDS) would I benefit from using 1 micron sediment and carbon block filters instead of 5 micron or would they just clog very quickly? I seem to go through DI rather quickly because the TDS out of the tap is 300-350 and there's probably CO2 in the water. Where I live in a condo without a basement I really have no room to let water sit in a bucket so the CO2 will evaporate then have a pressure pump to the pump it through the RODI so just replacing the DI more often is my only option. Next time I buy sediment, carbon block, and DI kit from BRS I'm going to pick up the inline TDS meter so I can test the TDS coming out of the membrane. I test the TDS of the water I use coming out of the DI for tank use with a hand held unit.

03/15/2015, 03:19 PM	#2
azjohnny Registered Member Join Date: Apr 2012 Location: Gold Canyon Posts: 2,914	I would get a TDS meter and test your water at these points. feed, post membrane and post DI. You shouldn't have to replace the sediment and carbon filters so often if they are a quality filter. Use as small of a pore size as you can, they serve to protect the membrane. You might also want to go with a better membrane 12 ppm out of 350 is a poor ratio ( 96.4%) I have 99% with a Spectrapure Select Plus. I have 650 ppm and get 6 ppm post membrane. I think your membrane has a lot to do with your problem. 60psi is ok, you would do better with more pressure pore size on the sediment filters sediment .2 carbon .5 the bigger the pore size the more they are letting through, the sediment and carbon do nothing to remove TDS