sump RO/DI?

[Silent Night]

i visited a friend recently, a proud owner of a 120gal FOWLER.
he has an RO/DI unit plumbed into his sump with a small submergible water pump in its own loop, so i guess he's purifying sump water and returning it to the cycle. i was a little sceptical. he thinks its a good idea. anyone tried it? is there any point?

i've always had mine plumbed into the mains with a saddle-piercing clamp.. lol

 

[neilanh]

Interesting concept. I would think that would not be a good idea, as it'd be pulling nutrients and stuff out of the water that one would want there.

Wouldn't that also remove salinity from the water???

 

[Silent Night]

from his point of view it only removes what a pwc would anyways, and he just tops up the salt as he usually would.

but its a concept that i have not seen before, so i though id ask.. lol

 

[Jimbo7]

I would imagine for a FOWLR it wouldnt be a bad idea, not exactly sure how much it is doing for him though. If you kept a reef I imagine it might be a little more influential.

 

[Silent Night]

thinking about it now, i guess that even if it is a FOWLR or a reef, it would only remove what a pwc would remove anyway.

i suppose if you ran about 15% of your tank water through the RO/DI in your sump, and it worked (lol) it may eliminate the need for a pwc... it would help to remove your excess DOC's and if your trace elements are lower (as they would be with a pwc using RO/DI) then you would supplement as usual.

i really want to find a fault with this! lol any ideas?

 

[Jimbo7]

Its going to remove a lot of trace elements that coral/invert require. You filter lots of crap out of the water to start with water as pure as possible, then add salt with all of the good compounds and elements we need. Using a filter on it again *i imagine* will remove a lot of that good stuff.

 

[Silent Night]

I agree, it will remove the good stuff too, but thats the same for a conventional pwc. You would still be replacing tank water with RO/DI either way. I see where you're coming from though. I'm sure he only turns it on for like two hours a week or something, so it's not stripping the tank.

Any other cons to this idea? I mean, if it was that simple everyone would do it.. lol

 

[Jimbo7]

The difference is with a conventional PWC you are then replacing what you took out with water of even higher levels thus boosting the overall level. Without putting anything in, you will slowly strip down all those trace elements.

 

[Silent Night]

But, doesn't a good RO/DI unit remove all contaminates from water, even those one may consider to be benificial. My 5 stage turns my water into what is essentially a blank canvas, to which I would proceed to add only the elements that I require to sustain my reef using various reactors and such.

Am I kind of making sense? I'm sure there is some logic behind this... lol

 

[David S]

he must have a huge top-up tank if the ro/di unit runs on a tank,plus I don't think the filters or membrains will last long,also is it ok to put salt water through these filters aren't they made for fresh water?

 

[ccCapt]

RO filters remove salt from the water. Desalination plants use RO filters to make freshwater from seawater. He may have a couple filter canisters in his sump, but if it's an RO unit, he's turning his saltwater into freshwater.

The Pros and Cons of Reverse Osmosis Desalination
"RO technology is pretty easy to understand, with plant designs consisting of pipeline and filtration sections.
The pipeline draws saline water from a local into a filtration plant. The plant consists of a series of smaller pipes filled with RO membranes. As the water moves through the RO membranes, they catch salt and other organic and inorganic materials considered unhealthy in drinking water."

 

[Silent Night]

My 5 stage removes salt of moderate concentrations, also. Good point about the membranes though. I guess if the sump has adequate sediment filtration so as to prevent larger particles entering the membranes it should be ok.

TBH, I think that the output of an RO/DI correlates to the quality of the input. I.e. filtering dirty water will be less effective as filtering moderately clean water.

He is most definitely turning his saltwater into freshwater, and then increasing salinity thereafter as required. lol I shall ask him all of these questions next time I seem him for sure. He lives in Wellington, New Zealand. I only visit him once a year when I vacate!

Has anyone tested the difference in quality? Fresh water vs. tank water?

It sure is an interesting concept! lol