reliable float valves

jimnrose · 07/05/2009, 11:51 PM

I'm planning to use two float valves; one to control the RO/Di feed to a 20 gal supply tank (located above the sump tank and the second to feed the sump tank from the supply tank. Reliability ifs the primary goal but also having a adjustible float valve for large swings in water level (+- 6"). Any suggestions??? Jim

jerryreefrigger · 07/06/2009, 06:27 AM

I've never had a problem with the float valves from airwaterice other than clogging with lime water. And I took care of that problem by drilling the hole out a little bigger. I have six valves in use for over 5 years, no float failures.

Why do you have such large level swings? 6 inches? Do you have a surge tank or something?

jimnrose · 07/06/2009, 07:17 AM

I'm new to the hobby and read on another forum that the RO/DI system operates better when it isn't turned on for small water quantities. The system will be feeding a 20g tank (12" high) that feeds (by gravity) the sump tank (29g). I thought the large arm swing would also reduce the activity on the float valve thereby possobly extending the reliability.
Thanks for your input; I'll check out airwaterice.

rick s · 07/06/2009, 10:09 AM

Many of us use, and are very happy with, this one. One nice feature is you can adjust the float after it has been mounted so you can change the water level in your sump if you should ever need to.
http://www.usplastic.com/catalog/pro...uct%5Fid=12596

jerryreefrigger · 07/06/2009, 10:54 AM

That's correct. RO systems work best when they produce water for an extended period of time. Using a float valve to compensate for evaporation in the sump creates a constant "low pressure" scenario for the RO unit. In other words, it doesn't allow the membrane to run through proper production/separation. This is what people call TDS creep. It drastically shortens the life of the membrane as well. The airwaterice website explains this too.

You're on the right track with your setup, however the float valve in the 20g storage tank will just follow what the float valve does in the sump, thereby creating the low pressure scenario. This is why people use float switches and a pump. I don't of any float valve that will wait to open. It doesn't matter how long the swing arm is. It will open up as soon as it starts to go down. You need your RO unit to fill the reservoir, 10 gallons at a time or so.

Here's how I do it. I don't like float switches and wires and relays and all the complicated stuff to create an ATO (auto top off) So, i've got big brute trash can for my RO storage tank. It has a float valve in it and the top is sealed to minimize evaporation. I have a small pump inside of it that pumps water up to the gravity tank (above the sump) . The gravity tank drips water through a float valve in the sump. (just like your plans) Inside the gravity tank, I have a high voltage float (just like the ones people have in their basement sumps) However, it's operates opposite of a normal sump float. Down in on, up is off. The pump in the trash can is connected directly to the float. As soon as the water goes down about 16 in the gravity tank, it kicks the pump on to refill it. This triggers the RO unit start making more water. (about 10 gallons worth) Until it reaches back up to the float valve.

Make sense?
The reverse float ball switches are available online for about 20 bucks. You can set the swing length however long you want. You just need to figure out something to attach it to.

jtma508 · 07/06/2009, 01:24 PM

From everything I've heard, Jerry's right about running the RODI system in short bursts. In my case, there was just no practical way to put a gravity feed or holding tank near my tank. So I decided to bite the bullet and drive my RODI directly as an ATO.

My ATO (and everything else) is controlled by my ReefKeeper Elite (RKE). I have a magnetic float swicth mounted in my sump that is monitored by the RKE. Rather than have the RKE turn on the RODI everytime the float 'goes low', I have programmed a timer that will run the RODI every 6hrs for 10min or until the float gets up to the normal water level. This does two things 1. it makes sure the RODI runs for awhile each time it's turned on and 2. it acts as a safety against an ATO free-running and killing the tank (and flooding). I have a 'high level' float that will trigger an alarm if the sump level goes too high from either ATO free-run or a return pump failure. I can adjust the cycle and run times to accommodate for seasonal evaporation rate changes.

This system has been running flawlessly for over a year. My RODI membranes are sill putting out 0 TDS water from well water that has an input TDS of around 115. So far so good.

jimnrose · 07/06/2009, 06:22 PM

Thanks for the information. I was wrong thinking the float valves stayed closed until the ball reached the lower level. I need to either find a mechanical solution like Jerry recommended (reverse float ball) or control the RO/DI with a timer over-ride based on a time frequency equivalent to a 12 to 14 gallon refill.
I'm off and running. Thanks again, Jim

jimnrose · 07/06/2009, 07:15 PM

BTW, does anyone know the evaporation rate/sf. I have 20 sf of surface area (125gal reef+ 29gal sump + 29 gal fuge + 20 supply tanks). I'm trying to guess how long it would take to draw down 14 gallons from the supply tank.

07/05/2009, 11:51 PM	#1
jimnrose Registered Member Join Date: Feb 2008 Location: The Villages, Florida Posts: 1,093	reliable float valves I'm planning to use two float valves; one to control the RO/Di feed to a 20 gal supply tank (located above the sump tank and the second to feed the sump tank from the supply tank. Reliability ifs the primary goal but also having a adjustible float valve for large swings in water level (+- 6"). Any suggestions??? Jim

07/06/2009, 10:09 AM	#4
rick s Premium Member Join Date: Jan 2004 Location: Chester, VA Posts: 2,993	Many of us use, and are very happy with, this one. One nice feature is you can adjust the float after it has been mounted so you can change the water level in your sump if you should ever need to. http://www.usplastic.com/catalog/pro...uct%5Fid=12596 __________________ Rick Current Tank Info: Reefer Emeritus

07/06/2009, 06:27 AM	#2
jerryreefrigger Premium Member Join Date: Dec 2002 Location: Oxford, MI Posts: 130	I've never had a problem with the float valves from airwaterice other than clogging with lime water. And I took care of that problem by drilling the hole out a little bigger. I have six valves in use for over 5 years, no float failures. Why do you have such large level swings? 6 inches? Do you have a surge tank or something?

07/06/2009, 07:17 AM	#3
jimnrose Registered Member Join Date: Feb 2008 Location: The Villages, Florida Posts: 1,093	I'm new to the hobby and read on another forum that the RO/DI system operates better when it isn't turned on for small water quantities. The system will be feeding a 20g tank (12" high) that feeds (by gravity) the sump tank (29g). I thought the large arm swing would also reduce the activity on the float valve thereby possobly extending the reliability. Thanks for your input; I'll check out airwaterice.

07/06/2009, 10:54 AM	#5
jerryreefrigger Premium Member Join Date: Dec 2002 Location: Oxford, MI Posts: 130	That's correct. RO systems work best when they produce water for an extended period of time. Using a float valve to compensate for evaporation in the sump creates a constant "low pressure" scenario for the RO unit. In other words, it doesn't allow the membrane to run through proper production/separation. This is what people call TDS creep. It drastically shortens the life of the membrane as well. The airwaterice website explains this too. You're on the right track with your setup, however the float valve in the 20g storage tank will just follow what the float valve does in the sump, thereby creating the low pressure scenario. This is why people use float switches and a pump. I don't of any float valve that will wait to open. It doesn't matter how long the swing arm is. It will open up as soon as it starts to go down. You need your RO unit to fill the reservoir, 10 gallons at a time or so. Here's how I do it. I don't like float switches and wires and relays and all the complicated stuff to create an ATO (auto top off) So, i've got big brute trash can for my RO storage tank. It has a float valve in it and the top is sealed to minimize evaporation. I have a small pump inside of it that pumps water up to the gravity tank (above the sump) . The gravity tank drips water through a float valve in the sump. (just like your plans) Inside the gravity tank, I have a high voltage float (just like the ones people have in their basement sumps) However, it's operates opposite of a normal sump float. Down in on, up is off. The pump in the trash can is connected directly to the float. As soon as the water goes down about 16 in the gravity tank, it kicks the pump on to refill it. This triggers the RO unit start making more water. (about 10 gallons worth) Until it reaches back up to the float valve. Make sense? The reverse float ball switches are available online for about 20 bucks. You can set the swing length however long you want. You just need to figure out something to attach it to.

07/06/2009, 01:24 PM	#6
jtma508 Premium Member Join Date: Jan 2008 Location: MA Posts: 1,232	From everything I've heard, Jerry's right about running the RODI system in short bursts. In my case, there was just no practical way to put a gravity feed or holding tank near my tank. So I decided to bite the bullet and drive my RODI directly as an ATO. My ATO (and everything else) is controlled by my ReefKeeper Elite (RKE). I have a magnetic float swicth mounted in my sump that is monitored by the RKE. Rather than have the RKE turn on the RODI everytime the float 'goes low', I have programmed a timer that will run the RODI every 6hrs for 10min or until the float gets up to the normal water level. This does two things 1. it makes sure the RODI runs for awhile each time it's turned on and 2. it acts as a safety against an ATO free-running and killing the tank (and flooding). I have a 'high level' float that will trigger an alarm if the sump level goes too high from either ATO free-run or a return pump failure. I can adjust the cycle and run times to accommodate for seasonal evaporation rate changes. This system has been running flawlessly for over a year. My RODI membranes are sill putting out 0 TDS water from well water that has an input TDS of around 115. So far so good.

07/06/2009, 06:22 PM	#7
jimnrose Registered Member Join Date: Feb 2008 Location: The Villages, Florida Posts: 1,093	Thanks for the information. I was wrong thinking the float valves stayed closed until the ball reached the lower level. I need to either find a mechanical solution like Jerry recommended (reverse float ball) or control the RO/DI with a timer over-ride based on a time frequency equivalent to a 12 to 14 gallon refill. I'm off and running. Thanks again, Jim

07/06/2009, 07:15 PM	#8
jimnrose Registered Member Join Date: Feb 2008 Location: The Villages, Florida Posts: 1,093	BTW, does anyone know the evaporation rate/sf. I have 20 sf of surface area (125gal reef+ 29gal sump + 29 gal fuge + 20 supply tanks). I'm trying to guess how long it would take to draw down 14 gallons from the supply tank.