[duster]

I'm thinking about setting up a 75g with a 20g basic sump. I'm trying to learn and figure out how to set this up, but am getting so confused. All this talk about internal and external overflows, siphons, gravity siphons, back siphoning, tweaking, etc. is messing with my head. Does anybody know of some good books or website links where I can read alot about this and see diagrams and layouts of sump systems? Everytime I read something in a thread that makes sense and answers questions, I read something else that contradicts it or brings up even more questions. Help.

[Reefland]

Hi duster,

I am not aware of a complete source for helping with these technicalities.

Here is the low down:
Setting up a sump is not difficult and will save you pain in the long run. The basic requirments for setting up a sump are the sump (can be a standard aquarium or a complex manufactured sump system), an overflow (either internal with a drilled tank or external) and a return pump. The overflow drains water from the display tank into the sump and the return pump pushes water back to the display. If the return pump will push more water than the overflow can drain then a valve will be needed on the pump output to regulate the flow.

It's pretty simple, any specific questions just let me know.

[duster]

I do have several questions for you. I will try not to overwhelm you all at once. I'm going out for the night soon, so I probably won't post again until tomorrow. Bear with me. Setting up a sump doesn't worry me, its the potential for overflowing tanks that bothers me. I had actually talked with you before about internal vs. external overflows. You directed me towards All-Glass. I have since decided to go with a 75g All-Glass tank employing their pre-drilled (bottom) Megaflow internal overflow system. This will flow into a 20g basic sump housing a protein skimmer, heater, and sensors. In a thread I was reading, you said "with a good overflow box, a power outage won't cause your siphon to break, just stop". How would a power outage stop a siphon? If we are talking about a simple gravity siphon, wouldn't the siphon continue into the open sump (until the water level in the main tank is below the siphon feed) regardless of whether or not the sumps' return pump is running?

[Reefland]

Ok, the confusion you have there is the thread you read was discussing external overflows that utilize a U tube to siphon water from the tank. Since your going with an internal overflow (drilled tank), you don't have to worry anything about the siphon because there isn't one.

With a drilled tank in the event of a power outage, the water level in the tank will drop just below the slots that are cut into the overflow. Normal operating levels (varies with different amounts of flow going through the system) is for the surface of the water to be about 1" above the bottom of the slots. This means that you'll need to ensure that the operating level in your sump is low enough that it will handle the 1" of water that will drain when the pump shuts off. In this case, if your water level while the pump is operating is 1" above the bottom of the slots, you'll need room for 4 gallons of water to drain into the sump in the event of a pump failure.

[duster]

Here is where my confusion still lies Reefland. If the internal overflow drew water only from the top of the tank, all my confusion would be solved. If you look at the downloadable brochure from the All-Glass website (http://www.all-glass.com/products/aq...flow_sheet.pdf), it shows that water is drawn from all levels of the aquarium, not just the top. It looks to me like the overflow has two chambers: the first chamber has slots cut into it at the top, middle, and bottom. Water flows into the slotted chamber until it is full, then spills over into the second chamber which contains the drain pipe. Will water continue to drain until the water level is below the lowest slot, which is near the bottom of the tank? Or will it only drain until it is level with the top of the overflow chamber(s), which, as you mentioned, would only be an inch or two below the top of the tank? Or, will water drain until the water level is below the drain pipes' intake? If you look at the accessory piping kit that you can order for the overflow, it looks like the drain pipe is adjustable. If the height of the drain is adjustable, and water would continue to drain until the intake is no longer under water, then couldn't I adjust the drain intake so it is high enough in the chamber that my sump could handle the drain off? Thank you for your time so far and I hope I am explaining myself good enough.

[middlemark]

Originally Posted by duster

It looks to me like the overflow has two chambers: the first chamber has slots cut into it at the top, middle, and bottom. Water flows into the slotted chamber until it is full, then spills over into the second chamber which contains the drain pipe.

Your description is excellent.

The interior wall, inside the `second overflow' is where the water will level out, which is only a few inches below the top of the tank.

While water is drawn into that first `chamber' of the overflow, it is only forced over that internal wall when the water outside of the overflow [in tank] is higher than that internal wall - only will go to the drain-pipe-chamber when the water level is above that internal wall or the external overflow - but both should be just inches below the top of the tank.

While the `outside wall' allows water from multiple levels of the tank to go over the internal wall - the internal wall is where the tank's water level [with sump pump off] will level out - normally 1/4" or so under the top trim of the tank.

The adjustable part of the drain pipe is so that you can adjust the water-level inside the overflow [and thus make it quieter by allowing a much shorter `waterfall' inside the final overflow chamber than if it crashed to where the bulkhead is].


Do you live anywhere near a reef club? This is one of those `hard as heck to explain, even to ask questions about' subjects that having you over to check mine out and have a beer would solve in a much easier [and more fun] fashion

[Reefland]

I think Mark has explained it well. The short of it is, forget anything that you have thought from looking at that picture. During a power outage, 1-1.5" of water is all that will drain from your display with this internal overflow.

[duster]

Good deal, thank you guys for clearing that up. I should have listened to you the first time you told me the water level would only drop an inch or two, but something about it was bothering me and I needed more assurance regarding the particular system I'll be using. Now that overflowing the sump from the drain line shouldn't be a problem, I have a couple questions about the return line. I read in a thread that if your return pump shuts down, water from the main tank will back siphon thru the return line into the sump. Will this happen? Could you simply install a check valve on the return line? If a return line containing a check valve was placed lower in the tank, could the check valve stand up to the pressure of, say, half the water in a 75g trying to back siphon thru it?

As far as a reef club middlemark, I'd have to check into it because it would be nice to have someone (in person) to guide me thru this. Problem is, I live in a small town with one little pet shop containing two small, simple fish-only tanks. They've never been too friendly or inquisitive in the past, so our relationship is all business. I guess I haven't been comfortable enough to start a conversation. Anyway, my success with saltwater so far has come from tons of reading and Internet research, including help from you guys. Much appreciated.

[duster]

Never mind about the return pump questions. I've been researching on the web all day and found alot of good info on sumps and plumbing.