Overflow box question


Reefing newb
I have decided to just do an under tank sump and was wondering if in order to do one, do I need an overflow box? Also I have a 40 gallon tank and was gonna do a 29 gallon sump. Is that too big or should I use something smaller.
If your tank isnt frilled then you need a overflow box. As far as the size of the sump...well the bigger the better. Most of us use the biggest we can get into the stand. Are you planning on sectioning the sump up? Running a refugium? lots of homework to do.
opps ya drilled...my bad :frustrat: I have many talents and typing is not one of them. I got my overflow box at aquatraders....was like half what a cpr costs. I have been running it going on three weeks and I have been very happy with it.
Personally, I'd go with the 1200gph box. That way you don't have to worry as much about over powering with the return pump.
Depends some 1200gph have dual hoses so you could always close one off if you are skimming to much water.

But yes if your tanke is not drilled get an overflow box but don't buy a cheap one, I bought one and it was crappy. The plastic screws broke that held the damn box in the water to adjust how much it takes in.

I love my CPR overflow box. on my 75 gallon. But you may have trouble fitting a 29 gallon under your stand. I have a 29 gallon under mine and I actually had to put it in from the top because it would not fit in from the back or front.
I have the 600 gph from aquatraders on my 45 for the return pump I used the 700 gph return pump that they sell as well. With the head loss I have no issue with over powering the box. To get the system super quiet I did a modification with the help of my local fish guy. Put a piece of one inch pvc to give it a stand pipe. I will take some picture of my setup and post them here in a few minutes. I basically bought everything from aquatraders...The only exceptions are the sump and the hydor power heads. Not was broken and everything seems to work really well. Was a savings of 50% for me.
Ok this is going to be a lot of pics I dont want to hi jack your thread so I wont load in photobucket. A few things The sponge in my overflow box has airline in the middle of it and a zip tie closing the top of the sponge. The sponge is hollow. I rinse the sponge every two days if not everyday. The piece of 1 inch pvc had to be sanded just a little on the end to get it to fit into the Chinese bulk head. Chinese bulkheads are tighter then the ones made here. I made a shelf in the sump for the skimmer to be at the correct level. Took a lot of trial and error to get it right. The skimmer is a ps75 from aquatraders also. In the refugium part I added some eggcrate to keep the cheato out of the bubble trap. There is live rock in this section as will no sand. sorry not a better pic of the refugium but there is a brace in front of it. The blue painters tape is to let me know not to put more water then the top of the tape. Very important encase of power outages. There is a hole drilled in the return just below the water line to break siphon in case of power outage. Oh I have a aqualifter pump connected to the overflow box to keep the siphon chamber free of bubbles and to insure the box will work when power comes back on. Yes I have diatoms...system has been running for three weeks. Its in my bedroom and silent. Yes the lights came from aquatraders as well. Ya i could have spent $1400 on this with out lights but I didnt have that so I went this way and spent $700 with lights. So far I have no complaints and have dry carpet. This worked for me, if it works for you great if it doesnt .well do what ya like.


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more pics....


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just a couple more...oh dont buy the drain and return lines from aquatraders they are crap. I bought different ones from my lfs. The drain line has the hose ends glued the traders ones werent. The clear return line is just that clear tubing that is what they use at the shop. new lines cost me about $25.


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Um two more things and I will shut up....Promise....in the middle of the tank you can see a hob filter intake. I keep that on the tank for flow. Most of the time I will run empty. When I want to run carbon I can just put the cartridges in for a few days. This also help getting the tank settled fast. Those cartridges got the crap out of the water quick. Thats the only physical media I will run. I also put a piece of lexan on the sump for my fuge light to sit on and keep it from getting wet. The sump has a interior shelf that it sits on perfect.
If your tank is not drilled it gets the water from the tank to your underneath sump. A sump provides more water for the system which makes it more stable. Also you can have refugium which is a natural filter. In my refugium I have live rock and cheato algae. The live rock provides home to pods and the cheato feeds on nitrates. The sump also provides a place for all the heaters, skimmers and crap you may not want in your tank. Another advantage of the sump is your tank will stay level. Water level in the sump will vary due to evaporation. You add your top off water also to the sump so the water is more mixed going into the display. I know this answered more then the purpose of a overflow but thats why people use them.