SpectraPure MaxCap Questions?

[vstar]

I have had my SpectraPure MaxCap 90 gpd for 2 years now and my ro membrane is doing 98.3%. I have always change my sediment and carbon filters every 6 months plus sterilizing the canisters. My TDS is always around 550. My questions is that I just made an order to SpectraPure for a new sediment filter and a new carbon filter. The carbon filter that I always buy for my unit says it is good for 20,000 gal. Do I still need to changed that carbon filter every 6 months as I usually only produce around 1500 gallon in 6 months or can I replace it like say once a year which would be around 3000 gal.?

[AZDesertRat]

You may be able to stretch the sediment cand carbon block replacements out further by monitoring pressure drop through the filter array and chlorine breakthru on the carbon.

I installed an additional pressure gauge on the incoming tap water before the sediment filter in addition to the one on the membrane housing which is after the carbon block. By comparing the two readings you can see headloss or pressure drop at a glance which is an indication of plugged or fouled filters.

I also purchased a low range chlorine test kit from Spectrapure and use it to monitor for chlorine breakthru which is indicative of exhausted, plugged or fouled carbon.

 

Using the combination of the two I can stretch the replacements out to a year or possibly longer but I usually chicken out at a year. Keep in mind, if you have made 1500 treated gallons 7500 gallons have actually passed through the sediment and carbon at the normal 4:1 waste ratio since even the waste passes through those two.

 

Spectrapure details their method of extending filter life in their FAQ section and on most of the Sponsors Forums they have.

[Formula462]

I have had a 70% drop in pressure and could not figure out why. I replaced the membrane, and the flow restrictor to no avail. So three days ago I ordered the 4 pack replacement (pre, carbon, silica buster, di resin) I was thinking the line from the carbon to the membrane was clogged or something but I ordered replacements to just see what would happen. After reading this it seems maybe the carbon stage was fouled and causing a drop in head pressure.

 

It used to run 50 psi just off the tap pressure, then I added a boost pump and shot it up to 80 psi. THEN, one day I turned the water on and it didn't even pull measurement on the gauge, and with the boost pump could only hit 35 psi or so. I didn't think it could be the carbon or pre filter because it read 0 TDS even before the DI stage. After changing the RO membrane and restrictor, the tds said something like 455.

 

Hopefully just changing everything all at once will fix it lol. I have also had my maxcap 90gpd for 2 years.

[AZDesertRat]

Sediment and carbon filters have very little to absolutely nothing to do with TDS. There are there to protect the RO membrane from suspended solids, collolidal materials and chlorine. TDS are in the 0.0001 micron range, sediment and carbon block filters are in the 0.2, 0.5 or 1.0 micron ranges, thousands of times too coarse to filter out dissolved solids. With before and after gauges you can monitor the headloss at a glance and prevent this situation. For every 15-20 or so psi you lose 1%-2% on your rejection rate and cut your DI life in half so it is worth monitoring often.

[vstar]

Thanks a bunch AZDesertRat, I knew I could depend on you helping me out as you have in the past. I will do what you told me about adding another pressure gauge. The pressure gauge that came with it always has shown me 62-64 psi and has never drop during a 6 month interval on the sediment and carbon block filters. Also we do not have chlorine treated water in our water system in our community at this point which is just fine with me. Also thanks for the heads up on the total water volume going through the my filters.