Lowering Nitrates from Fluconazole treatment

[Silverking90]

Before everyone jumps on the "google" comments, I just wanted to say, from what I've read on this topic, nobody else's scenario seems to be similar to my own.

Since my tank's start 8months ago, Ive always had a nutrient problem. I presume from over feeding corals. Ive liked to keep my nitrates around 15-20 as my tank is mostly a softie tank. I guess this elongated presence of nitrates (along with phosphates) ended up in a gradual algae bloom that had my tank covered in algae about 3 weeks ago. To rid the algae I ran Fluconazole. Im on my 3rd out of my 4 week treatment and the algae is almost all gone. Obviously this decay of algae made my once silent (0 nitrate and 0 phosphate) nutrient test results true with readings of 30 nitrate and .16 phosphate (red sea test results) (.03 phosphate with a hannachecker) measured today. As instructed with the Fluconazole treatment, im currently running no carbon and changing my gfo weekly, skimmer has always been and is still running. The release of once bound up phosphates seems to be managed well by my gfo, but the nitrates just keep rising.

During this treatment, what can I do or run to reduce the nitrates?? I just added bio pellets in a reactor yesterday and added a huge clump of chaeto into my fuge on Saturday (3 days ago). I know these 2 methods take time to show results but how long?

Further more, once my nitrates are lowered to my desired level (15-20) what is going to keep them from rising further, or worse, what is going to keep the algae from slowly growing back all over my rock work in the display?

Basically, what can I do that will keep me from having to repeat this cycle Ive just written about?? It seems to me that nutrient levels start out where u want them, and over time algae slowly starts growing (cuz I like 15-20ppm of nitrate), consuming those nitrates giving u false test readings. What starts out as a little algae growth with low nitrates soon becomes a lot of algae with low nitrates....its like the algae consumes all the nitrates giving u low test results, but even though the results are coming back low, the algae still continues to thrive and spread over time.

This would be an easy solution for nitrates if my goal was to keep them between 0-5 because the algae wouldn't have enough nutrients to grow at all in the first place. I desire to have 0 phosphates so I assume once those have been cleaned out, its as easy as keeping up with gfo changes and not overfeeding to maintain those.

Thanks for the help!

 

[Jose Mayo]

I do not know if I understand your concern, but as long as fluconazole is acting there will be no growth of sensitive algae, even with increasing nitrates and phosphates ... but if the concern is with the effects of nutrients on other beings in the aquarium, especially cyanobacteria that can grow by excess nutrients, or dinoflagellates or even zooxanthelas, making the corals darker or brownish, one solution is to control the excess nutrients with partial water exchanges, maintaining the same concentration of fluconazole in the water of replacement , until the algae are eliminated.

What will certainly cause the algae to return, is the early cessation of treatment, before eradicating them.

Regards

 

[mcarroll]

To rid the algae I ran Fluconazole.

This is kind of a crutch, or hack and doesn't take account of what's going on in your tank.

Going forward I would try to get a whole different outlook on nutrients as well as algae vs what led you to the antibiotic treatment:
Is nutrient control an effective method of treating algae in a reef? is a great thread to start with. (thanks again for starting it @rock_lobster!)

Algae is not something that needs medicinal treatment and nutrients are not something that requires removing.

Right now with 0.03 ppm PO4 your system may already be phosphate-limited. Consider the error rate of the tester and you're possibly measuring 0.02 ppm even when the screen reads .03. Phosphates that low are likely to cause nitrates to build up rather than being used up as things like growth, healing and reproduction slows down and stops all across the tank's ecosystem.

Your GFO can't remove the PO4 on the rocks and your tester can't test for it, so your algae winds up with a phosphate source that's unavailable to lots of other critters that need it and most of which would compete with your algae's presence in numerous ways. So you end up fostering a pro-algae environment that has lots of available nitrates to fuel it. (Not that algae are really dependent on nitrates in the water either.)

As your minimums for a healthy tank recovery, consider affirming phosphates at a level 0f ≥0.03 ppm and nitrates at a level of ≥ 5 ppm. At least in the short term, don't allow either one to go below those levels. As the tank matures this will matter less and less.