Thinking of new set-up.

[Kerry1968]

I currently have my little White's in a part aquatic tank, the bottom third is water. I'm hoping (when I can afford it) to get an Exo Terra 18x18x24" viv and make it more terrestrial.

I've been thinking about making a false bottom and having a waterfall-stream-pool effect in the tank. Does anyone forsee any problem with using a undergravel filter to move the water from the bottom of the tank to the outlet/waterfall? I've been looking at how these work and as I understand it an airline to the bottom of the uplift pipe is all that's needed to get the water flowing through.

So the layers I am think are - gravel or those clay balls on top the filter tray, with a corner clear for the pool, top this with a mesh of some kind to stop the substrate going into the water, then the substrate and plants on top this.

The thing is, an undergravel filter usually has water pulled down over the whole surface and in this case the water would be pulled kind of from one corner to the other, if you get what I mean?


Please excuse my VERY crude drawing!

[Wyomingite]

...Does anyone forsee any problem with using a undergravel filter to move the water from the bottom of the tank to the outlet/waterfall? I've been looking at how these work and as I understand it an airline to the bottom of the uplift pipe is all that's needed to get the water flowing through....

If I understand what yer proposing correctly, it won't work. U/g filters work on displacement. An equal water level is needed on the outside of the uplift tube and the inside, thus equalizing head pressure, otherwise the water will simply flow back down the tube because gravity is stronger than the uplift provided by the air. The air only pulls water up until it dissipates into the atmosphere, then it ceases to do work. To illustrate, I'll use 2" of water in the pool/across the bottom of the tank. You would have 2" of water in the uplift tube to begin with. The air will come out of the airstone, rise the 2" in the water column/uplift tube, then dissipate. It will pull water up the column for 2", maybe a little more if a very high air flow is used, then the water will drop back down the uplift tube. You'll end up with 2" of water in the uplift tube that is very turbulent and well oxygenated. Very little circulation of water will occur, and none of the water will rise up the entire height of the tube to provide your waterfall.

Priming the uplift tube with water to the top won't help either, again because there is no head pressure outside of the tube to prevent gravity from pulling the water back down the tube. If ya start with the air pump running and fill the tube, an ounce or two may go over and down the waterfall simply due to turbulence before gravity pulls the rest of the water down the tube and the level equalizes throughout the tank. If ya fill the tube without the air going, it's all gonna flow back down the uplift tube to the bottom and equalize with the water outside the tube, kind like fillin' a container with a funnel. At that point in either case, yer back to the previous paragraph with 2" of water across the entire bottom of the tank.

I don't know, physics was never my strength, in theory I suppose a strong enough air source may be able to pull the water up the entire heighth of the tube, but air is inefficient. The compressor needed to provide that kind of air volume and flow would be far beyond anything ya'd wanna use in a vivarium set-up, and ridiculously expensive for the application.

Unless ya have the parts on hand, by the time ya buy an air pump, decent air stones, the u/g filter and tubing, ya could buy a decent power head or small submersible pump and some 1/2" id tubing and accomplish the same thing for much cheaper anyway. Make a sump in the rear corner for the powerhead/pump and run the 1/2" tubing up to the outlet/waterfall.

WYite

[Kerry1968]

Yeah, I get you WYite. Thanks. Hmm, I thought there was something awry in my thinking! Ah well.

The problem I've now got is how to make the water deep enough so that I can work an underwater pump without swamping the substrate. Back to the drawing board.

[1beataway]

If you have a submersible pump, you wouldn't need the water to be very deep, right? I used hydroballs instead of a false bottom, but it still didn't seem like it was very deep. The problem I had was that a couple of corners of substrate weren't high enough, so I did swamp the substrate, and I had to get more hydroballs and "lift" up the corners so I could make them higher.

[Wyomingite]

1beataway is right, ya only need enough water to constantly keep the submersible pump covered, first to ensure the pump does not lose suction disrupting flow and second for cooling and lubrication to ensure the pump does not overheat and seize up. You'd only need enough water to ensure the pump stays covered plus 1/2"-3/4" (roughly 2 cm, just noticed yer in the U.K.).

WYite

[Kerry1968]

Thanks for the help guys, I'll have to have a think about which pump I'm going to use, I have a couple spare, one is bigger and more powerful (more likely to be able to pump the water high enough 'upstream') but will need more water to cover the intake. The other is smaller but may not be strong enough to push the water up the tubing.

Then I have to think about how I'm going to make the stream. I'm hoping to be able to find something suitable to just lay on the top of the substrate to make the bed of the stream, I'm not up for building with expanding foam, tapecrete, epoxy or any of that kind of stuff! I think it's going to be a long process!

[1beataway]

How about just rock for the stream?

In the past couple days, I was talking to a friend about how I could have made my first vivarium better (I'm already tempted to dismantle and start over again. ), and I mentioned a waterfall and stream, and though I haven't put -that- much thought into it, I thought just having a nice thick layers of rock that would create just a shallow area for water would work. Maybe.