12 hours of filtration?

[Sundance]

This may be one for the crank file, but...

What if...I ran my filters (sponge, HOB, canister, whatever) on timers like I do lights and only ran them for 12 hour cycles instead of the total 24 hours?

Will the water quality suffer to the point that would affect fish health?

I'm thinking that the consistent cycle would break up any surface film on a daily basis, thus aerating the water? The detritus of the day would still be pulled into the rocks/filter every day, just not during the night?

Fish keepers at the beginning of the hobby didn't have electric filtration, so...

Why? was probably your first thought. I know that the energy cost in the fish room is all ready inexpensive, but I'm on a conservation kick and reduction of energy use is the number one way to conserve. So, putting the why aside, what are your thoughts?

[fishbait]

Im not an old pro, but there are good and bad points to this.

good
1 ) saves money
2 ) saves wear on impellars
3 ) less cartridge changes

bad
1 ) time for bacteria to go bad
2 ) chance timer will screw up and not come on (thus produces more bad algae.)
3 ) filter will not efficiently exchange o2/co2

im sure there is more but i cant think of it right now

[mewickham]

Sundance,

Filters should run 24 hours per day. The main reason is that, when turned off, oxygen levels drop. This especially happens inside filters, where media blocks the easy flow of oxygen from the surface, and where decaying detritus consumes extra oxygen. This could cause a die-off of helpful, nitrifying bacteria in the filter. Would losing these bacteria be enough to destroy biological filtration in your aquarium? Probably not. The helpful bacteria are on every surface. But it wouldn't help.

Also, the detritus that is trapped in the filter media, in a low oxygen condition, could begin to denitrify. A different type of bacteria take over and produce stinky, hydrogen sulfide gas a by-product. Hydrogen sulfide is toxic in sufficient quantities. Denitrification can also turn relatively harmless nitrates back into toxic nitrites. Would the levels rise enough in 12 hours to be an issue? It depends.

Canisters filters have been known to denitrify and become toxic when turned off too long. Unlike hang-on-the-back filters, they have no access to surface oxygen. Then, when turned back on, the canister blows all the toxic water out of the filter and into the tank. It has been known to kill fish. It depends on how dirty the filter is, and how long it is off.

Another issue is plant respiration. We all learn that plants breathe CO2 and releas O2, but most people don't realize that the process reverses at night. Plants use oxygen when there's not enough light to photosynthesize. So, without circulation, in a heavily planted aquarium-- especially one heavily stocked with fish-- oxygen levels can become dangerously low.

Bottom line: run your filters 24 hours. They pull hardly any watts. Lights and heaters pull much more. Running an aquarium heater in winter is much more efficient than heating the room to keep the fish warm. With lights, the only real options are, perhaps, to choose more energy efficient types of bulbs. If you keep live plants, though, you don't want to cut back on the light. They need it to make food.

Here's a table I put together that shows how cheap it is, electrically, to run a typical 10-gallon aquarium:

wattage table.pdf

Electrical Consumption of a Typical 10-Gallon Tank

(18.76 KiB) Downloaded 64 times

wattage table.pdf

Electrical Consumption of a Typical 10-Gallon Tank

(18.76 KiB) Downloaded 64 times

[mewickham]

2 ) saves wear on impellars

Fishbait's post made me think of another reason. Often, when you turn a filter off, the bacterial slime on the impeller and in the impeller-well cause the impeller to stick. Or a piece of detritus can fall down the impeller-well and jam it. So the filter will not be able to restart until you disassemble and clean it. If you use a timer to turn it back on, you will not be there to know that the filter did not restart. Most filters are water cooled. Without water moving through them, they overheat, deforming the impeller-well, and ruining the filter.

When I was a dealer, the number one reason for return of hang-on-the-back filters was by customers who could not get them to restart after turning off the power to make a water change. When I showed them that disassembly and cleaning let everything fire back up, they were very happy not to have to replace the filter.

[pinkrblu]

I have had issues in the past with a filter, but can't remember immediately which filter it was. When I turned the power off to clean things, then back on, the first burst of water was full of detritus that had "settled" somewhere that I wasn't getting to when cleaning it. Therefore, my freshly cleaned tank was always full of tiny particles of crap.

[Sundance]

Thanks for the responses! Nice chart!

Considering your input, I won't be putting my canister filter on a timer. I was about to bring another one online as I fill my 130 ga, but now I'm considering an adequately sized linear air pump to run all the tanks in the room. (The 130 has a UGF as well) This would centralize my wattage and if my math is right be considerably less energy to filter my tanks, especially if it runs on a timer...

So, any cautions to a 12 hour UGF with plastic plants in the tanks? I'll also be running a powerhead/spraybar for surface agitation.

[mewickham]

Undergravel filters shouldn't be turned off, either. It probably won't be a huge deal in 12 hours, particularly if the gravel is clean, but I wouldn't do it.

[Sundance]

Thanks, Mike. I do appreciate it. I'm kinda looking for "why" the UGF shouldn't be turned off.

I think I'm going to experiment with one of my ten gallons for awhile to see if it affects tank health.

Thanks!

[mewickham]

It shouldn't be turned off for the same reason you shouldn't turn off the canister filter. All that detritus pulled down into the filter bed can go anoxic. Then you can get anaerobic bacterial action that can produce hydrogen sulfide or denitrification that can convert nitrate back to nitrite. Again, I don't know if 12 hours is long enough to do sufficient damage. It depends on several factors besides time-- the amount of detritus, the depth of the gravel bed, and more.

If you want to envision what can happen, maybe you can remember a time where you left a bucket of dirty gravel sit for a couple of days. The gravel at the bottom turns black and smells awful. That is the hydrogen sulfide smell from the anaerobic bacterial activity. Or think of the difference between the color and smell of pond muck from the top 1/2" depth, or from a few inches down. The top muck can absorb a little oxygen. The deeper muck can't.

Anyway, don't air pumps draw around four watts? Take that times 24 hrs/day and 30 days per month. You get 2880 watt-hours. Divide by 1000 to get 2.88 killowatt-hours. Multiply times $0.10 (the typical cost per kw-hr) and you get 29 cents per month to run an air pump. Turning it off for 12 hours would save half. Is it worth a risk to your fish to save 14.5 cents per month?

[Sundance]

Cool man. Appreciate the detail.

My calculations are for the scale of a small fish room (14 tanks, two of which are 100+ gallon) and I'm exploring energy options for long term consumption. Should I use all HOBs? Canisters? What are the savings of centralizing filtration with an appropriate sized single linear air pump? Combinations? Are there options out there that haven't been considered, like 12 hours of filtration? I'm not asking you to answer these questions, just trying to clarify that I'm not a mad scientist looking to experiment on fish to save 48 watts a day.

Thanks again for the info. I'm sure I'll have more questions soon.