Undergravel filters (Need advice and your thoughts)

[Toddo]

I'd also say that using air bubbles to try and draw water thru the gravel and up the tubes is just about useless.

You really need to use powerheads. (in either direction of course)

 

[spiff]

With air stones you get more lift and water flow.

I don't think that's true. But I do think that the finer bubbles of an air stone is better for surface agitation. But for just moving water, I doubt you can beat an open hose shoved down the pickup tube. The only down side I see to going open hose is that its louder, but that never bothered me.

 

[spiff]

I'd also say that using air bubbles to try and draw water thru the gravel and up the tubes is just about useless.

You really need to use powerheads. (in either direction of course)

I have never had problems with air power. With open hoses, my pickup tubes still spurt water even after I have dropped the water level almost a foot. You can't beat the effieciency of a simple bubble pump action. Just because you probably overstocked the tank, or have too much gravel, or whatever other reason it doesn't work for you, to say that something so useful and simple is "useless" is irresponsible.

Personally, if my air power ever stopped being enough, I would opt for more air powered pickup tubes before I wasted money on an comparably ineffiencient powerhead.

 

[CHOMPERS]

Actually the nitrate thing is another myth. This is guaranteed by the Conservation Law of Matter. A quick run down is that matter can not be created nor destroyed (nuclear reactions asside). The total nitrates are limited to what is put into the tank.

At the very worst, the UGF delays the release of organics into the nitrogen cycle, but that happens with any filter. This is countered with regular gravel vacs and water changes (nice that they happen at the same time).

The gunk that builds up under the plates is the last in the process of food and poo breaking down or is the last of the organics that takes forever (bone meal for instance). The bulk of the nitrogen products have already been removed from the organics before they reach the bottom of the plates. When the gunk continues to break down, it becomes dissolved in the water (dissolved organics) and is removed at the next water change. Any nitrogen products entering the nitrogen cycle from the gunk at this point is very minimal in comparison to the fish urine, fresh poo, and rotting food.

 

[Toddo]

<<I would opt for more air powered pickup tubes before I wasted money on an comparably ineffiencient powerhead.>>

So you're saying a pump with an impeller is less efficient than bubbles at moving water?

 

[spiff]

Actually the nitrate thing is another myth. This is guaranteed by the Conservation Law of Matter. A quick run down is that matter can not be created nor destroyed (nuclear reactions asside). The total nitrates are limited to what is put into the tank.

At the very worst, the UGF delays the release of organics into the nitrogen cycle, but that happens with any filter. This is countered with regular gravel vacs and water changes (nice that they happen at the same time).

The gunk that builds up under the plates is the last in the process of food and poo breaking down or is the last of the organics that takes forever (bone meal for instance). The bulk of the nitrogen products have already been removed from the organics before they reach the bottom of the plates. When the gunk continues to break down, it becomes dissolved in the water (dissolved organics) and is removed at the next water change. Any nitrogen products entering the nitrogen cycle from the gunk at this point is very minimal in comparison to the fish urine, fresh poo, and rotting food.

Good info, I was wondering about that. And maybe its just that goldfish reprocess a lot of their own waste with their substrate sucking behavior, but after 1.5 years in my goldfish tank, the bottom is still clean. Its a simple matter to look up from inside the stand to see what is happening under the UGF. I ever only cleaned the gravel every other WC, or once a month.

 

[spiff]

<<I would opt for more air powered pickup tubes before I wasted money on an comparably ineffiencient powerhead.>>

So you're saying a pump with an impeller is less efficient than bubbles at moving water?

Yes. My ONE bubbler which powers 4 pickup tubes moves more water than one powerhead which uses much more power.

 

[CHOMPERS]

I'd also say that using air bubbles to try and draw water thru the gravel and up the tubes is just about useless.

You really need to use powerheads. (in either direction of course)

Actually it is not useless, and has been done successfully for decades. Yes, the flow is low compared to a powerhead, but the flow rate is not important. Air pumps in general use less electricity than most powerheads, so they shouldn't be ruled out.

 

[Toddo]

Actually it is not useless, and has been done successfully for decades. Yes, the flow is low compared to a powerhead, but the flow rate is not important. Air pumps in general use less electricity than most powerheads, so they shouldn't be ruled out.

Ok, I'll agree that air will move water and does work (I used it for years)..but this is MFK and I was leaning towards the Monster side....

 

[CHOMPERS]

I don't think that's true. But I do think that the finer bubbles of an air stone is better for surface agitation. But for just moving water, I doubt you can beat an open hose shoved down the pickup tube. The only down side I see to going open hose is that its louder, but that never bothered me.

How lift tubes work is by a difference in density (weight of the water) inside the tube and out. The less dense water/air mixture will rise in the tube because it "floats" in the more dense "pure water". The greater the difference in the densities, the more boyant the lesser will be. The density of the water inside the tube is the average of the waters density and the air in the bubbles. Small bubbles are more prone to suspend in water than larger ones. Large bubbles from an open air tube tend to slip through the water, leaving the water behind. (The water actually pours down around the bubble.) The smaller the bubble, the slower it will rise. With the smaller bubbles suspended in the water instead of slipping through it, more of the air can be averaged into the density of the water.