RO filter/membrane questions

I've been real lazy in terms of replacing any of the filters on my Coralife Pure-Flo II (24 GPD). And by real lazy I mean I've had the system for 2 years, use it at least once a month, and have never changed anything. Anywho, its about time I changed everything: membrane, carbon block, micron filter. Just have a few questions.

1) Are the carbon/micron filters the same I'd get at home depot/lowes/walmart?

2) Which micron would you suggest for the carbon block and prefilter? 1 or 5?

3) Also how come there is such a large price difference between online vendors for the membrane? The membrane currently in my RO machine is a Desal TFM-24. I found it somewhere online for $26, while drfostersmith.com, although it doesn't have any brand name listed for whatever reason, has a 24 GPD membrane listed for $82. (picture looks exactly the same). This wasn't really a question, more of a mini-rant on the outrageous markups I see in this industry sometimes

 

The filters your unit came with are pretty low end, probably equivalent to those found at HD and Lowes but not what I would go back with.

You should go with no more than a 1 micron prefilter and an equal sized 1 micron carbon block, those woul be my bare minimum. Prefferably a 0.5 micron prefilter and 0.5 micron carbon block if you want good water quality and superior membrane life. Either the 1 or 0.5 micron will make the RO membrane last years longer since it is being protected better.

I would not go back with a 24 GPD membrane if it were me, painfully slow! You can fit a individually hand tested and guaranteed 90 GPD Spectrapure RO membrane in your unit for $45 or one of their batch tested 90 GPD membranes for only $35. Either would require a matched flow restrictor at like $5. Your is rated at 24 GPD at 65 psi and 77 degree water temp. Theirs is rated at 90 GPD at 60 psi and 77 degree water temp, thats about 4 times the flow with the same waste ratio and much higher quality water in the end. No more standing around watching it drip...........drip.........drip.

Check out their Customer Appreciation sale here:
SpectraPure Customer Appreciation SALE! 20% - 50% off

Whatever you decide on make sure you disassemble and disinfect the system with bleach before installing the new filters. Its a 5 minute job and is often overlooked.

 

thanks for the link. honestly I don't mind waiting around for it to do its thing, as I only have a 55 gallon and do at most 25% every other week.

Oh and good heads up on reminding me to disinfect the system... I probably would have just rinsed it out...

 

oh another question... what affect does water temperature have on the process? I'm fairly positive my tap water temp is much much lower than 77. Will that slow the output down?

 

Both temperature and pressure have major effects on GPD output, and water quality too believe it or not.
Take a look at the Calculator that Russ has at the top of the page here:
http://www.buckeyefieldsupply.com/

The smallest membrane he sells is a 50 GPD Dow Filmtec which produces 50 GPD at 50 psi and 77 degrees. Yours is only 24 GPD but more imprortantly takes 65 psi to produce 24 GPD since it is a GE Desal and not a Dow Filmtec. Dow would rate yours at about 16 to 18 GPD at their 50 psi. Play with the numbers and you can see pressure and temperature have a big effect. Tap water TDS also has an effect as does the waste ratio but temp and psi are the biggest factors.

My Spectrapure actually produces about 100 GPD at a true measured 64 psi and 68 degree water. It does not have to tie up a faucet for 24 hours to make water for a change or topoff. Thats what sucks about low GPD systems unless you have an out of the way place to hook them up.

Have you ever timed yours to see what it really produces?