RO membraane & hot water

sohal1025

Active member
I usually make RO with 50/50 hot/cold water. The flow is quicker when the water is luke warm as apposed to it being very cold this time of year.
The cold got turned off but not the hot and ran most of the night.
Will there be damage to the membrane?????
 
yeah, I think there is a max temp that they can hit. Maybe Melev will chime in he knows what it will do...
 
jbmynes is correct. Too hot water will cause the membrane layers to 'melt' together. I think the temp is 110 or similar. You might shoot Buckeye Field Supply or the Filter Guys a message in the sponsor forum.
 
My guess is if you were running pure hot water, the membrane is toast. Personally, in the future I think you are better off running a extra long coil (50-100') of tubing through a warm bucket of water prior to feeding the RO unit.
 
Hey, that's a great idea.

The only place I have for my RODI unit is in the garage. I have normally been giving up making water until the spring because of the temps.
 
Yeah the guy that came to speak a couple years ago said to aim for 77 degrees. I suggested running a coil of tubing as a pre-heater and Russ from Buckeye Field Supply said to watch out for pressure dropping due to restriction of the coil. I used 150 ft of plastic RO tubing and just dropped it into my sump. That way it should always be 77 degrees.

It seems to work well for me but be aware of the pressure issue.

If your input temp drops from 75 to 45 degrees then production will be cut in 1/2.

I guess one way to prevent the pressure drop might be to use 3/8" plastic tubing for the pre-heating and it should supply the RO system easier.

I'm also pretty sure that he said ANY amount of time with 140+ degrees would cause damage to the membrane. I would test your water with a thermometer to be positive and then send Russ a PM or post in his forums.

http://www.reefcentral.com/forums/forumdisplay.php?s=&forumid=446

Good luck!
 
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You could pull the tube between the RO and the DI and test the TDS of the water going in and out of the RO membrane .
Most are 98% rejection rated so if you have 200 TDS in you should be around 4 out. Your DI resin could be working overtime to get the final output water near 0 but testing the RO output will eliminate that variable.

Hope that helps
-- Kevin
 
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I always thought the goal was zero coming out? I guess I've been lucky with my tap water, tds is usually under a 100 closer to 80 so I get 0 output tds. I no its time to change filters when I start showing 5 or so. That takes me about a year to go up to that.
I still use the tds meter You did the group buy on Kevin. How long are those things accurate?
 
I use that one too. I would say yearly calibration wouldn't hurt but I haven't done it yet.
I meant the TDS out of just the RO membrane should be reduced by around 98% of what goes in. The DI should finish getting you to zero.
 
Buckeye FS said that a membrane is only warrenteed to 115 degree. He also said that id the product water is god, then the membrane is good. BUT....like itZme said, test after the RO and before the di. If you get less than 25ppm and near zero after the di your ok.
 
<a href=showthread.php?s=&postid=13899324#post13899324 target=_blank>Originally posted</a> by Kreeger1
I always thought the goal was zero coming out? I guess I've been lucky with my tap water, tds is usually under a 100 closer to 80 so I get 0 output tds. I no its time to change filters when I start showing 5 or so. That takes me about a year to go up to that.
I still use the tds meter You did the group buy on Kevin. How long are those things accurate?

Consider yourself lucky. When I replace my DI resin, I can get about 100gallons before my TDS creeps to 2-3. In a nutshell, I pretty much need to replace my resin every 4-6weeks.
 
Now the TDS meter is reading 006.
My dual Spectra meters are reading (in 116 and out 001) on first meter and (000 in and 000 out) on the second meter.
What do you guys think I should do?
 
Well the handheld TDS meter reads 006 but the dual meters read 000, so does the handheld one need to be calibrated and if so how is that done?
 
Anything at 113 degrees or higher voids the Filmtec warranty (but may not damage the membrane). Bottom line - check the membrane with your tds meter.

Russ
 
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