Yes, the sump will sit on the floor next to the cabinet it is sitting on.

Robert

Is the 55 drilled on the bottom?

No way! :) The terrarium is made of tempered glass. Can't drill tempered glass! At least I can't.

The feed and returns will be over the top at one corner of the tank where the waterfall will be.

Shortly I plan to start a new thread in the Terrarium Gardening forum tracking the progress of creating it ("it"=for orchids (of course:blushing:)).

Robert

How do you plan on getting water to return from the tank to the sump? If you're thinking you'll pump it back down, start thinking differently!

Terrarium questions
 

Oh good question! I'm loving this thread. I want to build a natural looking waterfall in my terrarium too, but have no idea where to get started so I'm learning a lot!

I understand where you're coming from and, indeed, it may be a tricky situation but hopefully I've got that covered. The main problem will be to fill the return tubing before starting the pump the first time. Once it is running it will be a closed system and the only reason for the "sump" will be cooling the pump. Granted this is all theoretical: the weight of the water returning down the return tube should balance the weight of the water being pumped up the feed tube. If that is, indeed, the case there won't be much load on the pump.

Whether or not this will work in reality depends on how hot the body of the pump gets (bearings mostly). I'm expecting the amount of water in the "sump" will keep the pump cool enough. There are two reasons I expect this system to work: 1) the motor is thermally protected and 2) the water moving thru the pump provides the cooling for the shaft seal. Also the "sump" is a plastic container

There are only two caveats I can see here: 1) filling the return tube (not quite sure how to accomplish that yet) and 2) how warm the water in the tank becomes, can't have it get too hot for the orchids. I don't anticipate the sump water getting too hot as the sump will be on the floor which stays relatively cool even in the summer.

So to this extent this is an experiment. Guess I'll have to run the system before the orchids are introduced.

If worst comes to worst the pump will have to be in the tank. I don't want this as I want to have as much growing space in the tank as possible. Too, to have the pump in the tank would mean three inches of water.

Robert

---------- Post added at 12:02 PM ---------- Previous post was at 11:49 AM ----------

Actually I've been going over stuff here that properly belongs in the Terrarium Gardening section which I suppose I should get started on it. The plan now is to record the process step by step with pictures. So wander over there in a couple of days. It will be a learning experience for both of us (and others).

Robert

So there will be a sump. How much water in the sump? What happens when the siphon breaks? It will pump all the water from your sump into the terrarium and flood it. Its sounding more and more like your best bet is to increase the depth of the water and use a submersible pump in the tank.

Not going to work Robert. Your design requires you to, from a physics standpoint, have your cake and eat it too, in that you are trying to combine an open system with a closed system. In a closed system you could indeed get all the air out of your return tube and have water return nicely to the sump. But a waterfall is by definition an open system, which will allow air in which will stop your siphon. I've been installing and maintaining aquaria professionally since the early 90s, and if I had a nickel for every time I've heard someone want to try what you are planning I'd have a few bucks. If I had a nickel for every one I've actually seen, I'd have a nickel, and if I had a nickel for every one that worked long term I'd be broke! The only sensible way to get water from the main tank to the sump is gravity. The only non-sensible way that works is to use a second pump on a float switch, which will one day fail. In your case that would result in a burned out pump in your sump. In the one case I've seen of someone actually doing it, they ended up with about 20 gal of saltwater on their floor. You are correct in that tempered glass can't be drilled. If you want to run a waterfall in an undrilled tank, you will end up putting the pump in the main tank. Save yourself a lot of wasted time and design around it. This is not an opinion, it is physics.

:blushing:
You've made me think :hmm. The pump would only fail if the water level in the tank fell below the siphon inlet so it seems to me that if one continually checked the water level and added water as needed the system should continue to work.

In any case I'd planned to make a mockup of the system to check it before actually installing it so if it fails, well, at least I won't have installed it and find it went kaput. :_(

As for the waterfall introducing air into the system I can't see how that might happen since any air introduced thus wouldn't get into the return tube since it will be immersed in a pool of water.

***Thought experiment: Put two pipes into a large watering trough and the other two ends attached to a pump of some sort, start the pump or hand crank it. It should pump until the water level drops below the suction pipe. So would that be considered an open system or a closed system? Either way it will work indefinitely (or until the water level drops too far).

In any case I appreciate your input.

Robert

Water splashes. Splashes are air mixing with water. However since your system as laid out is an open one, a bit of air may not matter. But if enough gets in to break siphon, yyou'll burn out the pump. One way of addressing your concern about water depth with the pump in the main tank would be to install an elbow on the intake. This would allow the pump to function in much shallower water.