Good bacteria in HOB filter

[WhoDatDSant]

So I did a water change last night and my nitrates went up a large amount.

Im guessing due to me cleaning out the inside of my HOB filter very thoroughly instead of just rinsing off the media.

So whats going to happen??? Should I move my fish to my 10 gallon tank, do another water change? Any advice would be great I guess its another lesson learned the hard way

[thegrun]

How high are your nitrates? Are the fish showing signs of stress? I would make a water change rather than change tanks; even a large water change would be less stressful than a tank change.

[ynot65]

Lose the HOB filter, what size tank is it and how much live rock do you have?

[Reeferz412]

Nitrates wont kill your fish even if they are on the high side. Switching systems and moving fish would stress them even more. I run an AC110 that I clean every few months or so. The high flow inside doesn't let anything stay down there too long and all I run is chemi pure and a few pieces of rubble rock with my DIY scrubber that is on the output. I doubt cleaning the HOB filter caused high nitrates.

[Salty Dog24]

That's what I was thinking, not sure how cleaning a HOB filter would spike your Nitrates. Unless you cleaned it in the DT, after the water change.

[Chevrefils]

HOB's are great I run an emperor 400 biowheel with a skimmer on my 75. HOBs are great at pulling out crap, just clean it often!

[dppitone]

Nitrates probably won't harm the fish but will feed algae growth. Do a water change to compensate.

[asylumdown]

nitrates going up after a water change to me sounds like you've got nitrates in your source water, or your test kit is wrong. Are you using RO/DI water or tap water? I'm not sure what the standards are where you live, but in Canada it's legal to have up to 44.5ish ppm nitrate in drinking water (or 10ppm nitrate reported as N). For some cities that level can fluctuate pretty wildly over the course of the year.

Cleaning a HOB filter will not cause a nitrate spike. The end result of a functioning HOB filter is nitrate, so if you've killed all the bacteria in it you'd expect less nitrate, not more. Did you clean anything else that might have disrupted de-nitrifying capacity in your tank? For example an aggressive sand vacuuming could wipe out anaerobic areas that may have developed, or released a bunch of trapped organics in to the water column.

[brandon429]

good food for thought:

100% of people here would agree that bioballs are a nitrate factory.

so, why is a hob not one

[Chevrefils]

good food for thought:

100% of people here would agree that bioballs are a nitrate factory.

so, why is a hob not one

Hob filters are very different from bio balls. Hob filters can contain filter floss or carbon. Essentially they do what a skimmer does on a smaller scale. It won't pull dissolved organics out but you can trap them before they dissolve. Just rinse it each week and it will continue to do a great job. Also you can modify hobs to be surface skimmers. I'm confident I can pull off my skimmer and keep my parameters nearly the same with my biowheel. I just like the dual job of skimming and filtering. I find it ridiculous everyone hops on the HOB filter nitrate factory bandwagon. They are very efficient and can easily handle coral tanks with low bioloads.

[asylumdown]

Not to be too nitpicky, but whether or not you can put carbon or any other media inside a HOB filter has little to do with whether or not that HOB filter will be a net source of nitrate in an aquarium.

That filter floss that's trapping organics would also need to be thoroughly rinsed far more often than once a week for it to not be a source of nitrate. The aerobic heterotophs that decompose things like uneaten food can reproduce several times an hour. As an experiment, you should intentionally trap a piece of mysis shrimp in that filter sponge and measure how long it takes to dissolve to the point where you can no longer tell what it was. I promise you it is faster than a week, it might actually be faster than 1 day in an established aquarium. As it is being decomposed by those heterotrophs, it's producing ammonia, which then flows through your biomedia and is converted to nitrate by a different group of bacteria, and since the biomedia you'd put in a HOB filter is too small to develop any truly anoxic conditions, that nitrate will simply be added to the water column.

You can put whatever media you want in the HOB filter and that will still be true (unless you put in a nitrate absorbing resin of course). Whereas a skimmer takes un-eaten food and physically sequesters it from the water column before any breakdown occurs, a HOB filter allows decomposition to take place within the water column every second of every day. Rinsing it out once a week at best prevents whatever you fed that morning from becoming nitrate, it does nothing to stop what you fed the previous 6 days from becoming nitrate.

HOB filters, canister filters, bioballs, etc. are designed to do primarily one thing: provide facultative surface area for the aerobic processing of nitrogenous wastes. They do this very effectively and efficiently. The end result of that process is nitrate, so even if you're cleaning the filter floss twice a day, the end result will still be a net positive output of nitrate.

This isn't a criticism of HOB filters. I think they have their uses and have been aquarium work horses for decades, it's just important to understand what it is that they're doing and their role in a system.

[brandon429]

And the winner of the thought brainstorm concepts check is:

:)



My ponderance really doesn't contribute much to the thread its more to bring to light strange things I see in our preferences as reefers. Disturbing waste pockets, or a total misreading depending on the test kit or interpretation could be at play to produce the brief spike mentioned here.

Most likely I'm the only one out on this limb, but to expound further I don't even think bio balls are as bad of nitrate factories compared to live rock and thats completely opposite of conventional thought

The idea centers around the theory of nitrate reducing zones vs the actuality of people still needing bio pellets to get nitrate reduction in spite of tanks stacked with quality live rock. For all these years I'd read about live rock reducing nitrate into n2 gas, then I'd measure nitrate in my own tank with 6lbs of very hq cured rock per gallon and no detritus issues. I knew something was up in this pervasive theory just off watching my own tanks

Degassing certainly occurs, but its not measurable for the bioloads and dilutions we run. Its a neat theory though.

[FTDelta]

Ditch the HOB filter. A protein skimmer do a far better job keeping your tank clean and clear. Plus not to mention the easy cleaning/maintaining a skimmer is.

[SantaMonica]

nitrates going up after a water change to me sounds like you've got nitrates in your source water

I'd say this too. Unless your HOB was growing algae inside it, which would have absorbed the nitrate.

[Chevrefils]

I'd say this too. Unless your HOB was growing algae inside it, which would have absorbed the nitrate.

I should point out that's what I do on one side of my biowheel. I grow chaeto and GHA pops up inside that chamber but never in the display. The other side I run carbon and filterfloss in front to catch debris. I pull that filter floss/ media out daily when I feed and switch it with a new one. The old one I rinse and soak clean to be switched later. It takes less than a minute just like cleaning my skimmer collection cup. I run my tank with tap water which I mix for 2 days to allow evap of chlorine, have no cyano, no GHA in display, and great growth from my corals. To each their own as long as It makes you happy.