Reusing Water Change water again after refreshing it

[ZoWhat]

So it seems the main reason to change out water on your Reef is to export nitrates and phosphates

Those of us with large water volumes of 250g or more just 'sigh' at all that money going down the drain as old salt water.

Sustainability is the hot topic nowadays ....so....

Anyone with a large system ever taken on the task of KEEPING the old saltwater, say 100gals+, in a vat container.... and over time REWORK the used saltwater by nearly zeroing out the no3 and po4.... while getting the Calc, Alk, Mag and Traces back in line also???

Then take the REWORKED, REFRESHED saltwater and use it again as 'nearly-new' during a water change?

I'm curious... bc I think i.might take this project on and refresh old saltwater and during a WC use 50% brand new SW and 50% refreshed SW

To replace 200g of SW costs roughly $50-$80 depending on the brand of salt mix. I betcha I could refresh 200g for a 1/4th that price. It would just be a time investment project

.

 

[blaxsun]

Nope. 200-gallon system, 2 water changes in 6 months. I’m less than 1/4 into my first bucket of salt this year (after the initial bucket to setup the tank).

 

[ZoWhat]

SIDENOTE on the process:

To refresh the old SW, I'd use the vodka (ethanol) method to nearly zero out nitrates

For phosphates, I'd use lanthanum chloride to zero it out... while filter socking the LaCl out

For Calc, Alk, Mag, I'd use traditional dosing methods to get things back in-range

For minor and trace elements, I'd use dosing products from companies like Brightwell

Again, to replace 200g of SW costs roughly $50-$80 depending on the brand of salt mix. I betcha I could refresh 200g for a 1/4th that price. It would just be a time investment project

 

[Hincapiej4]

I haven't done a water change in a while...

Once your tank is in a groove, It handles the no and po pretty well on it's own with minimal input.

 

[Hincapiej4]

Probably end up NEEDING no3 and maybe po4 after a while..

 

[LeftyReefer]

Again, to replace 200g of SW costs roughly $50-$80 depending on the brand of salt mix. I betcha I could refresh 200g for a 1/4th that price. It would just be a time investment project

Exactly, so what is your time worth? the time it would take to do this? Seems like a lot of work and not much gain in the end. I've never paid over $50 for a bucket of salt, so this just doesn't seem worth it to me.

 

[T-J]

I've basically gone to no waterchanges on my 120g tank. Tank keeps itself in balance for N and P. I use All For Reef to replace trace elements. Not sure what I'd gain from basically doing the same thing outside of the tank that's happing inside the tank.

 

[JohnMzreef]

Low nutrients is old school at least in the context of mixed reef. Water change is for replenishing trace minerals and maybe exporting something like potassium if you dose potassium nitrate.

 

[Seneca]

Refreshing your old water is just as easily accomplished without removing it from your tank. Lots of people don't do water changes (including me aside from replacing water lost to skimming). There was a point after I left my tank for about a year (it was automated) that I had very high nutrient levels, 300+ nitrate and 4pmm+ phosphate (lost no corals, but they weren't happy). I got the nitrate down by adding a sulfur denitrator, and I initially got the phosphate down by doing a mini version of what you suggest. Turned off my sump and treated the sump water heavily with LaCl, and reconnected it after letting it sit over night. I did this several times until I got the overall phosphate level under 1. Then I added phosguard and slowly brought it down to 0.2.

Initially I used LaCL at recommended rates using a filter sock and killed a yellow tang, and the rest of my zebrasoma tangs were all breathing heavily for a day. Disconnecting my sump and treating sump water totally isolated totally solved that issue even when I added 200 times as much LaCl into my skimmer intake and brought phosphate down from 3 ppm to zero over 3 hours, and reintroduced circulation 12 hours later.

My hypothesis was that it was totally ok to drop phosphate levels very fast if they were super high and only begin the slow drop once they were below 1 as I couldn't imagine anything that matters in the tank actually needing phosphate levels over 1 ppm. In my tank this appears to have been accurate as everything seemed happier after I brought the phosphate down 3 ppm in a week.

In the future I'm hoping my acetic anhydride dosing will take care of both nitrate and phosphate (the sulfur denitrator is disconnected, though I still run some phosguard as I'm still leaching excess phosphate from rocks).

Its also worth pointing out that though my nutrient levels were unquestionally bad, even with levels that high nothing died (mixed reef, no acros, several montis and other sps and lps)