Has anyone filtered aquarium water through RO to use again?

[Aquatic Journal]

Hello,

This is a random question but I’m curious if anyone had done anything similar. I am looking to setup a fish room where there is no running water. 3/4 of the year I can just run a hose in for water changes but during the winter that will be a bit hard. I’m curious if anyone is setup a water purification system to purify the water coming out of an aquarium to reuse during the next water change? 

[StephenP2003]

It seems like it would mean replacing the filtration/membrane much more often, but not sure if it would be cost prohibitive or not. 

[Ben_RF]

Though I do not know for sure, but these are my thoughts, I imagine it would be similar to reusing reject water from the RO.  What happens when you do that is a large increase in scaling that fouls the RO system.  So most likely you would need to use it injunction with a tubular membrane system to reduce the scaling before reusing it. 

 

Edited September 14, 2020 by Ben_RF
clarity

[Sykes]

Not sure what your goals are with this fish room, but I think your better route might be to take the 9 'up' months to get your tanks cycled and seasoned, heavily planted, and understocked so you can (hopefully) avoid water changes for 3 months. Will likely still have to bring in some water to replace what's removed by evaporation and cleaning filters, but a lot less than you would otherwise.

In theory a filtration system like your describing should be possible (this is essentially what municipal water utilities have to do), but I suspect it'd end up costing more than buying RO from your LFS for every water change.

[Daniel]

11 hours ago, Ben_RF said:

I imagine it would be similar to reusing reject water from the RO. 

As @Ben_RF points out, it is similar to using the reject water. My system does this by having a second membrane in line with first membrane. It is called a 'water saver' system.

The reverse osmosis system works by sending pressurized water through a membrane. The issue I see would be introducing the aquarium water back into a pressurized system. The first solution that comes to mind is collecting aquarium water in to a holding container and then using some sort of booster pump to pressurize to water enough to make the RO system work.

But in theory at least, this is possible.

I think in my water saver system the ratio of product to reject is 1:1.5 which probably as good as you will ever get. So if you were able to get this to work you would still require a significant input of new water with every water change (for the same sorts of reasons perpetual motions machines require inputs of energy from outside the system).

Edited September 14, 2020 by Daniel

[Aquatic Journal]

10 hours ago, Sykes said:

Not sure what your goals are with this fish room, but I think your better route might be to take the 9 'up' months to get your tanks cycled and seasoned, heavily planted, and understocked so you can (hopefully) avoid water changes for 3 months. Will likely still have to bring in some water to replace what's removed by evaporation and cleaning filters, but a lot less than you would otherwise.

In theory a filtration system like your describing should be possible (this is essentially what municipal water utilities have to do), but I suspect it'd end up costing more than buying RO from your LFS for every water change.

Thanks, I think this isn't a bad idea. And it isn't as much about buying RO water but about hauling gallons of water into my fish room in the winter. I have 265 gallons currently running which means a 20% water change would be over 50 gallons (10 5 gallon buckets to haul). I am basically trying to avoid doing that whenever I want to do a water change. 

Thanks for all your input guys!

 

[Ben_RF]

I checked in with our water treatment guys at work and they pretty much told me something very similar to what @Danielsaid above. And yes the term he used is correct called a 'water saver' system.  And without spending a fortune, @Daniel is correct that the best you will get is around 1:1:5 .

Edited September 14, 2020 by Ben_RF
accidentally hit enter

[Ben Ellison]

One side idea I could see working is having the used water pumped into plastic bins full of plants l. Let the plants eat all the nitrates then back into the tanks. Basically hydroponics 😀