Nitrate crashes

[ryguy]

Ok, I gots me a question.

I was thinking about this last night and couldn't figure out exactly what occurs in this the following situation that can make it so volatile. When a wet/dry is used, we know that over time it can become a nitrate "factory" and eventually cause a crash. My question is, what is the scientific process of this?

 

[TCTFish]

Wet drys are less likely to be nitrate factories as filters like undergravel filters which are the worst and shouldn't even be considered. They are death traps of disease. On all filters, you want to keep them clean...hoses, tubes, mechanics like the propeller and it's housing. A crash is when nitrates are so saturated that the rest of the bio sort of clogs up. The nitrites will start to back up and then ammonia. It's like the opposite of when a tank is establishing bio where it goes from ammonia to nitrite to nitrate with each one zeroing out in the end whereas in a crash...it goes from nitrate to nitrite to ammonia with values high off the chart. It's simply too much saturated waste in the system. When nitrites begin to back up when nitrates are high, then you know there's not enough bio to support the waste load.

This isn't exactly a scientific description, but does explain what happens.

 

[ryguy]

Thanks,

I'll give you the situation that worries me and let you tell me if it has potential of causing a crash.

I have my overflow emptying into the first chamber of the sump. I have bioballs in there to diffuse the MAJOR bubbles created in this chamber. The sole reason for the bioballs is diffusion. I also have a small linear piece of filter floss stretching across the inner lip of the first baffle as water flows over it (to help out as well). Then comes my fuge and then a over-under baffle into the last chamber. bewtween the over-under baffle, (about 1 1/2" wide), I have more bioballs, with the purpose of keeping algae out of the main tank, and a layer of filter floss across the balls to minimize remnant microbubbles.

Do I have a potential "si-chi-a-tion" that I need to worry about? The floss gets brown rather quickly, and I replace it every two weeks or so up to this point.....

Just wondering if this type of setup requires that much maintenance, or more?
It does a good job at solving the problem though.

 

[TCTFish]

You may want to cover the first chamber of bio balls with a floss to trap waste debris before they have a chance to settle on the bio balls. This would help avoid excess accumilation on the bio balls as well as other areas in the sump. If you feel the need to have to rinse any of the bio media, do so in used tank water so the bio isn't compromised. The first media water going into the filter should be a mechanical media (floss and sponges), then chemical, if any, like carbon, then biological such as bio balls and ceramic rings and the refuge. This order of media will help achieve more effective filtration.

It's best to prevent a crash than to treat one and they key here is to keep nitrates under control. 05 ppm in reef. The best approach in keeping nitrates under control is to avoid over feeding and over crowding. That's where the waste originates from to begin with and an ounce of prevention is certainly worth a pound of cure. Especially in this hobby.

A sump set up is one of the easier and more effective filtration units to run maintain.

 

[steve-s]

Actually the only fall back of these systems is the lack of proximity to denitrifying bacteria. Wet/dry's and the like are highly aerobic which makes it very difficult for facultative bacteria strains to gain ground. They are still there but in such insufficient quantity they do nothing in terms of nitrate reduction. The key here is to provide areas close to the aerbobic stage of the nitrogen cycle so proximity permits fast use of nitrates converting them instead of entering the water column.

If you can place a sufficient amount of LR/base rock after the intitial aerobic area of the sump, you will greatly reduce the level of nitrate. As always though, export of nutrients (skimmer/water changes/algal harvesting) before they break down is still by far the best process.

Cheers
Steve