RODI top off question

alexkharden · 01/13/2016, 09:03 AM

So I'd like my rodi tank to shut the unit off when the rodi tank is full. Easy enough with a float valve.

I'd also like it to not turn on again until the tank is almost empty. How do I do that?

I've read over and over that short cycling a rodi system is bad, both for the membrane and the tds levels going into your di. If it kicks on every time the float valve opens then that could potentially be a lot of short cycling.

Is there some way I could control this with my apex, like with a solenoid valve and float switches or something?

Thanks!

Jscwerve · 01/13/2016, 11:10 AM

It could be done independently with two float switches, a solenoid, and two relays. As far as using an apex I wouldn't have a clue as I've never touched one.

outy · 01/13/2016, 11:19 AM

Set it on a timer to come on 30 minutes a day.

Works for me.

alexkharden · 01/13/2016, 11:35 AM

Quote:

Originally Posted by Jscwerve

It could be done independently with two float switches, a solenoid, and two relays. As far as using an apex I wouldn't have a clue as I've never touched one.

I know how the float switches work, and the solenoids. Relays?

alexkharden · 01/13/2016, 11:38 AM

Quote:

Originally Posted by outy

Set it on a timer to come on 30 minutes a day.

Works for me.

That would work for the normal ATO, but when I dump the whole thing into my saltwater mixer every couple of weeks, 30 minutes might not be enough to fill it back up again.

It would definitely work for my original question though, which was to stop the short cycling from happening.

Thank you.

JWClark · 01/13/2016, 11:45 AM

I just check manually and fill when near empty. If you know the average draw down time you can estimate when you need to start checking.

I use 44 gal brutes as a reservoir and fill the one plumbed to the RODI about once every two weeks. Every fourth week I need to fill the saltwater reservoir and the RODI reservoir at the same time (so every other week end). Just wake up Saturday morning, turn her on (I pre-flush) and go from there. Sunday morning I post flush and shut the system down (turn off the water supply). I also flush every 4-6 hrs or so if I remember.

The more complicated it gets the more potential points of failure.

MacPhisto · 01/13/2016, 11:47 AM

You need two float switches one on the bottom of your tank and one on top. Connect this so that both down is 'fill up' and both up is 'off' that way your RODI is never going to short cycle.

alexkharden · 01/13/2016, 11:50 AM

Quote:

Originally Posted by JWClark

I just check manually and fill when near empty. If you know the average draw down time you can estimate when you need to start checking.

I use 44 gal brutes as a reservoir and fill the one plumbed to the RODI about once every two weeks. Every fourth week I need to fill the saltwater reservoir and the RODI reservoir at the same time (so every other week end). Just wake up Saturday morning, turn her on (I pre-flush) and go from there. Sunday morning I post flush and shut the system down (turn off the water supply). I also flush every 4-6 hrs or so if I remember.

The more complicated it gets the more potential points of failure.

So, I'm thinking. Maybe a float switch at the bottom of the barrel that activates a light? That's pretty simple. I'm trying to automate something to keep from having to climb up to look into the barrel all the time (it'll be kind of high).

So, manual shut off for the RODI, and float valve at top to shut off when full, and float switch at bottom operating light to let me know when I need to open the manual? Sound reasonable?

alexkharden · 01/13/2016, 11:51 AM

Quote:

Originally Posted by MacPhisto

You need two float switches one on the bottom of your tank and one on top. Connect this so that both down is 'fill up' and both up is 'off' that way your RODI is never going to short cycle.

Float switches to a breakout box, breakout box to a normally closed solenoid?

alexkharden · 01/13/2016, 11:53 AM

Or rather, switches to the breakout box, and then Apex activates an EB8 plug to open the solenoid. (Sorry, I'm new to the Apex thing)

MacPhisto · 01/13/2016, 12:00 PM

I do not have an Apex, but something like this is possible i guess.

Redman88 · 01/13/2016, 12:02 PM

http://reefcentral.com/forums/showthread.php?t=2546574

going to get the parts and set it up on my next days off.

alexkharden · 01/13/2016, 12:08 PM

Quote:

Originally Posted by Redman88

http://reefcentral.com/forums/showthread.php?t=2546574

going to get the parts and set it up on my next days off.

Thank you, although I definitely do not understand that diagram yet, lol. Probably need to ask a bunch of questions to get that one down.

Redman88 · 01/13/2016, 12:23 PM

no worries i hoping i take the time to take lots of pictures. and also why i posted the block diagram.

alexkharden · 01/13/2016, 12:37 PM

Lol, yes, I'm hoping you do that too!

JWClark · 01/13/2016, 06:27 PM

If your main concern is knowing when it is low (I just tap and listen for the hollow sound) I've seen some folks doing the following:

Put a small bulkhead in the top and bottom of the tank then run a clear tube between them. Water will fill the tube to the level of the container water, going up and down accordingly.

My biggest worry with automating is that you will then assume it is always working. With my personality, I'd be checking anyway just to make sure, making the automation useless. Also, if you don't have automatic flushing on your RODI unit you are going to have to flush manually when it runs. If you don't, membranes and DI resins will fail prematurely.

n2585722 · 01/13/2016, 09:34 PM

I do what you are describing with my Archon. I use the float switch function with 2 float switches and a solenoid valve. The bottom float triggers the float switch function on and the top float switch turns it back off. I also have a float valve just incase the float switch fails for some reason as a backup.

More than likely some one has done this with the Apex also.

01/13/2016, 09:03 AM	#1
alexkharden Registered Member Join Date: Dec 2015 Location: Evansville, Indiana Posts: 336	RODI top off question So I'd like my rodi tank to shut the unit off when the rodi tank is full. Easy enough with a float valve. I'd also like it to not turn on again until the tank is almost empty. How do I do that? I've read over and over that short cycling a rodi system is bad, both for the membrane and the tds levels going into your di. If it kicks on every time the float valve opens then that could potentially be a lot of short cycling. Is there some way I could control this with my apex, like with a solenoid valve and float switches or something? Thanks!

01/13/2016, 11:45 AM	#6
JWClark Registered Member Join Date: Jan 2014 Location: MD Posts: 576	I just check manually and fill when near empty. If you know the average draw down time you can estimate when you need to start checking. I use 44 gal brutes as a reservoir and fill the one plumbed to the RODI about once every two weeks. Every fourth week I need to fill the saltwater reservoir and the RODI reservoir at the same time (so every other week end). Just wake up Saturday morning, turn her on (I pre-flush) and go from there. Sunday morning I post flush and shut the system down (turn off the water supply). I also flush every 4-6 hrs or so if I remember. The more complicated it gets the more potential points of failure. __________________ Back after a 13yr hiatus--much to my wife's dismay. Though she sure loves looking at the tank and feeding the fish! Current Tank Info: Reefer 450 seed tank for the retirement 315gal Reef Savvy build.

01/13/2016, 12:02 PM	#12
Redman88 Registered Member Join Date: May 2013 Location: Artesia, NM Posts: 649	http://reefcentral.com/forums/showthread.php?t=2546574 going to get the parts and set it up on my next days off. __________________ -Robert- 01101000 01100101 01101100 01101100 01101111 00100000 01110111 01101111 01110010 01101100 01100100

01/13/2016, 12:23 PM	#14
Redman88 Registered Member Join Date: May 2013 Location: Artesia, NM Posts: 649	no worries i hoping i take the time to take lots of pictures. and also why i posted the block diagram. __________________ -Robert- 01101000 01100101 01101100 01101100 01101111 00100000 01110111 01101111 01110010 01101100 01100100

01/13/2016, 06:27 PM	#16
JWClark Registered Member Join Date: Jan 2014 Location: MD Posts: 576	If your main concern is knowing when it is low (I just tap and listen for the hollow sound) I've seen some folks doing the following: Put a small bulkhead in the top and bottom of the tank then run a clear tube between them. Water will fill the tube to the level of the container water, going up and down accordingly. My biggest worry with automating is that you will then assume it is always working. With my personality, I'd be checking anyway just to make sure, making the automation useless. Also, if you don't have automatic flushing on your RODI unit you are going to have to flush manually when it runs. If you don't, membranes and DI resins will fail prematurely. __________________ Back after a 13yr hiatus--much to my wife's dismay. Though she sure loves looking at the tank and feeding the fish! Current Tank Info: Reefer 450 seed tank for the retirement 315gal Reef Savvy build.

01/13/2016, 11:10 AM	#2
Jscwerve Registered Member Join Date: Jan 2006 Location: Colorado Posts: 309	It could be done independently with two float switches, a solenoid, and two relays. As far as using an apex I wouldn't have a clue as I've never touched one.

01/13/2016, 11:19 AM	#3
outy Moved On Join Date: Oct 2004 Location: auburn CA Posts: 4,021	Set it on a timer to come on 30 minutes a day. Works for me.

01/13/2016, 11:47 AM	#7
MacPhisto Registered Member Join Date: Feb 2014 Posts: 65	You need two float switches one on the bottom of your tank and one on top. Connect this so that both down is 'fill up' and both up is 'off' that way your RODI is never going to short cycle.

01/13/2016, 11:53 AM	#10
alexkharden Registered Member Join Date: Dec 2015 Location: Evansville, Indiana Posts: 336	Or rather, switches to the breakout box, and then Apex activates an EB8 plug to open the solenoid. (Sorry, I'm new to the Apex thing)

01/13/2016, 12:00 PM	#11
MacPhisto Registered Member Join Date: Feb 2014 Posts: 65	I do not have an Apex, but something like this is possible i guess.

01/13/2016, 12:37 PM	#15
alexkharden Registered Member Join Date: Dec 2015 Location: Evansville, Indiana Posts: 336	Lol, yes, I'm hoping you do that too!

01/13/2016, 09:34 PM	#17
n2585722 Registered Member Join Date: Aug 2008 Location: Cedar Park, Tx Posts: 1,072	I do what you are describing with my Archon. I use the float switch function with 2 float switches and a solenoid valve. The bottom float triggers the float switch function on and the top float switch turns it back off. I also have a float valve just incase the float switch fails for some reason as a backup. More than likely some one has done this with the Apex also.