Auto-Topoff directly in sump?

Anybody see a problem using an RO float valve connected directly in sump for auto-topoff? The reason I ask is because I don't have that much space under my tank, so if I do make an external rodi reservoir it would be directly above the sump.

What are the advantages of an external container for topoff? I already know for flood control, but in my case it would not help since it would be above sump anyway and would overflow into tank if there were to be a problem. I already know how im going to get the water into the tank (float swiches,solenoids,valves).

 

The first thing I think about is the scale of the flood if you have a problem with it. If you have an external reservoir and the auto topoff runs away you're going to end up with a couple gallons on the floor, and maybe none on the floor if your sump has some extra head space on it, as most do. If you plumb your RO line directly in there and it fails right after you go to bed, or before you leave for vacation for a couple days you could have a LOT of water on the floor.

There are very thin (just a few inches thick) and tall reservoirs I've seen people use that don't take up a large footprint and can hold at around 6 gallons if I remember right. I think usplastics.com is where they get them.

 

I am not sure how you would do it w/o an external RO/DI reservoir. Do you have your planned diagrammed out? That would help me visualize your question. Then again, maybe someone already knows the answer without needing a diagram. I would need the pic though.

 

I understand what you mean, but in my case the reservoir would have to be mounted right on top of the sump. So if it floods its going to go in my tank anyways.

I'm pretty sure the way I'm doing it is fairly fail safe. My real question is, if the container serves any other purpose than just for flood control, such as dosing,etc..? Im also wondering about the life of the ro membrane turning on and off constantly.

 

I think I understand now. The question is whether to plumb directly to your main RODI tank or add a second small reservoir to control the amount the of water that could accidentally end up in your tank. Do I understand correctly?

 

One other benefit to a reservoir is that if your ATO gets stuck (even with the redundancy) you may not affect the salinity too much with only a couple gallons available. If you plumb directly to RO you could drop your salinity by a lot.

Also a lot of people use kalkwasser in their topoff water and you need a reservoir for that, maybe something to keep in mind.

In the end it's up to you and your tolerance for risk. ;D

 

IBMGeek im so glad you started this thread because i was going to do it just like you, not that its bad i just did not know and thats why im here....sorry to interupt your post

 

I guess I can always get a dosing system in the future. Only thing Im concerned is if the constant on and off of the rodi will affect its membrane life?

Here is a basic plan of what I was thinking.Click to zoom in.

 

That's a good point as well about the cycling of the RODI unit. I believe you are supposed to run it for a minimum amount of time each time you run water through it.

 

I use a container with float valve because my RO unit is in the basement and my tank is upstairs. It also has the benefit of limiting flood potential to what is in the container which also places a limit on how far down the salinity can drop if there is a leak. I use a storage container with a hole drilled in the side for mine. I placed it directly on top of two pieces of 2x4 sitting on the sump.


I used a Coralife float valve and built my sump with a piece of plexiglass inside with a bunch of holes drilled in it so I can place the valve at any height of my choosing.