Refuge offline = Nitrate spike ?

[dakar]

Got a theory to run by ya'll... Our 180g setup is presently a 45g rubbermaid sump and a 20g long tank for a refuge that is about 95% tightly packed chaeto and a littlemisc other macros, MJ1200 pumps water from the sump to the far end of the fuge and a weir box connected to the sump for a return, rough guess is a little over 200 gph through the fuge, this weekend while disassembling my skimmer i leaned my hand on something to gain some leverage, crack, dead weir box. So I had to take the fuge offline for about 18 hours or so (powerhead used to keep the water moving around in there). the day prior I ran the water and came up with zero's across the board. Fuge was offline for almost a full day waiting for the repaired the weir box and the fuge back online, this evening I ran my usual tests and nitrates had jumped to 35-40ppm (ran it twice to be sure).

Long story, now my theory; since all fish have been accounted for and nothing else has really changed short of the daily doeses of baking soda via top offs, think it is really possible that the fuge/macros could really be consuming that much nitrate to account for the tremendous spike?

I did notice the skimmer was pulling more than usual and darker skimmate. Coral are mostly softies and LPS and don't seem to be adversly affected yet, and no significant HA growth, so it looks like I caught it in time. Bio load is really light given the water volume of 250g total. I did a 30 gal WC tonight and will continue this daily until they get back under control.

But if this theory holds any weight at all to explain the spike, then anyone not running macros and a fuge should really take note.

Thoughts?

[davejnz]

Sounds reasonable to me to assume that the macro is uptaking all that NO3.I think with macro fuges,systems can become somewhat dependent on the algae uptake rather than bacterial processing although i'm sure with time the bacteria would catch up.I dont have any macro fuges on my tanks but if NO3 starts becoming detectable,i'd probably have to add one.

[dakar]

Interesting viewpoint, never considered that my bacteria population could be lazy, or just not established enough to handle the load if the macros are eating up the majority. Only about 200lbs of LR. Assuming everything is true then my next course of action will have to be to investigate would be the source of all that NO3, given the light load and large water volume, that's a tremendous amount of NO3, something's generating an awful lot of wastes. No wonder my macro growth has been so rapid. Sounds like an upgrade to the cleaning crew is on the short list as well, it's fairly light now. Maybe another 100lbs or so of LR after Uncle Sam gets his cut.

[Whoyah]

Maybe you could replicate the event (minus breaking the weir box) and see if the same thing happens. Perhaps only 12 hours to prevent such a large spike. I would also guess if your macro is really doing all of that work then the spike would drop once the fuge came back online.

[bjpembo]

i agree that its very possible. after all the fuge is a filter and with any filter if you remove it from the system of course it cant do its job anymore and anything that it was filtering is now going to be free to increase within the tank, especially if there is a steady producer, regardless of what that might be. think of it this way. if your pouring salt into a bucket over your tank your salinity isnt going to increase but if you mvoe the bucket (the filter) then as the salt starts to increase in the tank because its not being filtered out anymore then your sg levels will increase. i think this is what happened with your fuge. you took your major nitrate consumer out of the loop so the nitrate begain to build. i agree with whoyah, take the fuge back offline to test in more controlled conditions.

[dakar]

Thanks for the input, recreating the conditions sounds reasonable.... I figure if it were just a 10% WC last night mathmatically there should be a minor lessening of nitrates after a 24 hour period, but now the fuge is back online, if there is any substantial reduction of NO3, then that would validate my theory a bit more.

Once I get things settled back down to 0's across the board I'll try taking the fuge offline for short periods of time and see what happens.

The thought just hit me, since I can isolate where the water enters and leaves the fuge itself I want to run some nitrate tests there as well..... might yield some interesting results.

[hr:3552e91bbd]

Pro2K are you following this thread? Might provide a bit more insight for your new setup and how and why a refuge was recommended.