Overflow Box???

[dberrong]

I just recieved my overflow box in the mail and after checking it out, I have a question. Everyone seems to be concerned about the sump overflowing if the power fails, but noone seems to mention what will happen if the power fails and the siphon is broken in the overflow box then the power comes back on and the sump gets pumped back into the tank. I think Melev answered this question for me saying that the siphon shouldn't break even when the pump stops. The box that I got has a siphon tube from one box to the next and if the pump stops from the sump, then the siphon will empty the box in the tank and thus the siphon will break! If the power comes back on the entire sump will pump back into the tank and overflow the tank. Am I missing something or am I correct?

[roadcrew]

the tank water will drop to the lowest hole of the inside box then quit running in. the outside box has two compartments to it. the u tube goes in the side opposite the drain, and this chamber will hold water above the opening of the u tube. the other chamber will drain to sump. the inside box will level out with the level of water in the outer box chamber. the u tube ill not lose its prime because both sides are submerged.
when the pump comes back on the water fill tank overflows into inside box all starts as it should. but to answer your question, if your power goes off and for a some reason you lose the prime in the u tube your main tank will over flow till the sump is empty. if the u tube is installed correctly it should never lose prime.
mine will collect bubbles in the u tube but i do a daily burping. to purge them out. i can explain if you need but like i said before, set it up follow directions i will work! once you see it the pieces fall into place. good luck and keep a towel nearby. :)

[Grue]

Had this problem myself in the past. Now I just Drill holes in the bottom of every tank I use =) With a few bulkheads and a stand offs for the tank. The water will never drop below the level of the standoff. On other side of the tank I do the same for the return. Perhaps you will think of this in the future. Pics in my Gallery
Grue

[melev]

I have another article to come out in about a week that goes into this topic. Take a close look at this picture:

http://www.melevsreef.com/acrylics/demo_install/overflow_box.jpg

See the outer box? There is a section of white pipe that is at least 2" higher than the bottom of the submerged U-tube. That water level never gets lower, so siphon is maintained.

And once you have it running, you absolutely should simulate a power outage by unplugging your return pump several times, each time watching to make sure the overflow box maintains its siphon. After all, if you aren't home when a power outage occurs, you want it to resume as soon as power resumes.

[dberrong]

Thanks guys. Now I get it. I'm just one of those people that over analyze everything. I finally have most of the parts for my sump project. My glass baffles ended up being too wide for the tank, so I'm thinking about placing them at a diagonal so that I don't have to go get new baffles. Does anyone have any thoughts of the strength that the baffles may lose if they are not at a 90 degree angle with the tank walls but around 100 degree angle. In theory it will do the same thing, but I don't know about how strong the silicon is to hold them. Any thoughts?

[melev]

If they were 1/4" thick, I wouldn't worry. Unfortunately, you have window pane glass that is too thin and brittle.

[dberrong]

Plumbing question for the overflow box. The outer box has a tube that is about an inch and a quarter. Do I get PVC that slips over top of that? What size do I get? Or do I get 1 and a quarter inch PVC with a connector that I glue to the tube? Any suggestions of what I need to purchase?

[dakar]

Ummm... maybe my eyes really are going bad.... I can't seem to make heads or tails of your pic.... or maybe it's sideways...can't quite tell. Assuming from the finished edges and all it looks like a commercially purchased product, what brand/size is it?

Perhaps you can upload a pic that's not so close up as well?

[dberrong]

That pic is from the bottom of the box. I bought it off ebay. It looks almost exactly like the pic Melev posted. My pic is of the tube that flows for the overflow to the sump. Does that make sense? The box inside the tank would be the box to the left. The box is actually laying on its side on my table. You can see the clear siphon tube inside the box also.
Here is a link to the exact box I purchased. It says it is 500gph.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360009635271&ssPageName=MERC_VIC_RSCC_Pr4_PcY_BIN_Stores_IT&refitem=360006230071&itemcount=4&refwidgetloc=closed_view_item&usedrule1=StoreCatToStoreCat&usedrule2=CrossSell_LogicX&refwidgettype=cross_promot_widget

[dakar]

Now that makes sense! Sorry for the cornfusion, but I think you have the right idea there, I'd add a union in there and go with a slightly smaller sized pipe/tubing going to the sump. If the downpipe is smaller than the one in the overflow it will run a lot quieter

If you've heard the continuous toilet flushing sound you know what I mean... makes for lumps on the skull magically appearing in the middle of the night... not sure how I know that.... :)

[dberrong]

Should I glue the union? I didn't know if that was typical practice. I also edited my previous post to provide the link to ebay for the exact box I purchased. Now that I read it I could have bought hose that would fit the thing, but of course I didn't do that. :)

[dakar]

With the union in place you have the option of cementing the PVC in place or not. After learning the hard way, proper cementing is a good way to guarantee the water does not end up on the floor (this equals more lumps), and the union will let you clean and move things around later.