RO/DI filter question

[Koop]

I got a ro DI filter when I purchased a whole used setup. I hooked it up today and was surprised that some of the canisters did not fill up all the way. The TDS meter says water in is 035 and water out is 000. So that seemed good. I was also surprised how much water was going down the drain compared to coming out filtered.
Any input would be helpful.
Thanks

 

[dpulve]

I do believe even with the perfect water pressure and temperature your still looking at a 4 to 1 ratio of waste water. I ran mine back to washer and I know some people use theirs for plants ect...

 

[Koop]

WOW 4 to 1. i thought is was going to be like 1 to 1. What is the perfect temperature and pressure? My pressure tanks runs between 40 and 60 lbs and the room is between 62 and 68 degrees.

 

[kmbyrnes]

Sounds about right. As long as you get 000 TDS out you are fine. If it gets over 001, change out the resin. Change your filters every six months.

I sure wouldn't be concerned about the cost of the water going down the drain.
You can re-use it if that is your concern.

http://www.reefcentral.com/forums/showpost.php?p=22415386&postcount=31

 

[Koop]

Fortunately I have a well not municipal water so it doesn't really cost me anything. I just wasn't sure if I have it hooked up properly since it was used with no directions or labels. The first two filter are filled with water but the last two stay nearly empty unless I shutoff the filtered water outflow. They will then fill up. But as soon as I open the outflow water comes out quickly, the filters nearly empty and the flow returns to the normal trickle.

 

[sfdan]

The air in the DI section doesn't matter as long as the bottom part of it has water, but if you don't like the look of it you can bleed out the air by slightly loosening the DI cartridge while the unit is running, letting the air bleed out, then tightening when the water level reaches the top.

 

[CStrickland]

It's normal for air to be in the di cans.
Are you reading 35 from the tap, or from the ro?
Well water can have high co2, which depletes the di extremely rapidly; and low pressure which reduces membrane function. Your pressure is on the low end. A booster pump might be in order. If you start burning through di, you might need a tank to off gas co2.

To know how the unit is running you need to measure
- tap pressure (65-80 psi)
- ratio of waste to product water (collect each for a minute and measure volume. 4:1)
- temperature (measure after its run 10 minutes or so. The ratio estimates are based on 65f)
- tds for the tap, post ro membrane, and product (the ro needs to remove high90s% and post di can't ever not be 0)

Don't forget to clear your tds creep

 

[Koop]

Ok. So I need to measure TDS after the RO and after the DI?
What is TDS creep?

 

[Koop]

My pressure never gets above 60lbs. Does anyone have recommendations on booster pumps? How critical is the extra pressure to operation?

 

[Greybeard]

I'm running an RO/DI on a well system. Pressure tank is about 60psi, which is pretty normal. You might look into a permeate pump. This will raise the output pressure to the same as the input pressure. Since I have a pressure tank of RO water, the permeate pump allows that pressure tank to have the same pressure as the main well head pressure tank.

Oh, and I try and use the waste water... goes into my pool during the summer, but this time of year, it's going down the drain.

 

[fishchef]

I've read on RC that RO/DI on a well will deplete the resin very quick. Do a search for postings. FYI

 

[Sk8r]

Be aware too, that the cylinders don't all wear out at the same rate, and that once you own the unit, replacing the cylinders is not that expensive.

You will need a 'strap wrench' if you don't have one. They give you this nice little plastic jobbie-thing with the filter, but there's a suction that sets up that can make those cylinders worth a hernia to try to undo. A strap wrench is a wonderful thing to have around the house in general: I've even used it on stubborn jars and plumbing.

 

[CStrickland]

Ok. So I need to measure TDS after the RO and after the DI?
What is TDS creep?

Yeah, as well as the other things I listed.
Tds creep is the first few minutes of water off the membrane being dirtier because stuff travels to the clean side of the film while the unit is not in use. If you don't bleed that off when you start making water it wears out ur di, and gives a false high tds reading after the membrane.

 

[d0ughb0y]

I got a ro DI filter when I purchased a whole used setup. I hooked it up today and was surprised that some of the canisters did not fill up all the way. The TDS meter says water in is 035 and water out is 000. So that seemed good. I was also surprised how much water was going down the drain compared to coming out filtered.
Any input would be helpful.
Thanks

you did not say if you replaced all the cartridges with brand new ones. I think it is not filling up because they may be due for replacement already.