what size pump?

[567234ta]

In the drawing below is a basic layout of my situation. The return line to the tank has to come in at the bottom of the tank which is 150 gallons. The height difference in sump water level to tank water level is about 3.5 feet. Not sure if i need a stronger pump because of this back siphon pressure or not.

I was planning on an external Iwaki japanese motor pump for the task. Not sure what gph i should go with though. Sump will hold about 50 gallons.
I will use a check valve of course as if the pump stops the tank would reverse flow until dry.

http://www.ls1truck.com/upload/files/1/lobstertank.jpg

[shifty51008]

i would go with either a panworld 50pxx or 150ps of a pump simular size. but I would be more worried about the check valve failing (which they do quite often) why is there not a overflow box in the tank and run a durso? I would breathe much better that way

[567234ta]

i would go with either a panworld 50pxx or 150ps of a pump simular size. but I would be more worried about the check valve failing (which they do quite often) why is there not a overflow box in the tank and run a durso? I would breathe much better that way

well the drain will be in the center on top like a normal overflow drain, just in the center of the tank, I adjusted my pic. I just didn't draw it exactly as that was not my focus of my question.
I am going to get the george fisher wye check valve and have a shutoff valve after it on the line, if it fails it will flood my garage floor which wont be a big deal, and i guess the way the tank is it will hold about 8 inches of water keeping the sand and rock wet, giving a place for any fish to stay submerged also.
You think the panworld 50pxx is a good enough quality pump that i wont have to worry about it failing?

http://www.ls1truck.com/upload/files/1/lobstertank1.jpg

[thor109]

It might not hurt your garage but when your tank drains and all live stock is lost you will think its a big deal. It needs to be fail safe. I would never put a line at the bottom. If you really want water coming in at the bottom run it up and back down. With an air hole to break siphon

[shifty51008]

the panworld was just an example Iwaki would be a good pump also, I think a 1200gph+ pump will work fine.

ok now i understand the drain but why not have the return come up to the top of the tank also? the only lines I would run where they enter and exit on the bottom of the tank would be for a closed loop otherwise you will still run the risk of floods.

[567234ta]

It might not hurt your garage but when your tank drains and all live stock is lost you will think its a big deal. It needs to be fail safe. I would never put a line at the bottom. If you really want water coming in at the bottom run it up and back down. With an air hole to break siphon

yeah i know and i have never ran a tank like this before nor would i in a regular setup, but this is a unique tank.

This might be a better pic of what is happening. The water will come into the bottom area where there is a chiller coil,the green coil, (this tank will be in a room that will be 90F sometimes) Then above that is an acrylic floor with the drain hole in the center,2" and 2 1" holes that the return will push water thru. The 2 1" holes will have elbows which will create a circular current somewhat.
So if it did back drain it would only go down to the tops of the 1" pipes before it broke the siphon. That would leave water in the section between the acrylic floor and the pipes, about 8 to 10" of water. Although im hoping it never happens.
http://www.ls1truck.com/upload/files/1/lobstertank2.jpg

[567234ta]

the panworld was just an example Iwaki would be a good pump also, I think a 1200gph+ pump will work fine.

ok now i understand the drain but why not have the return come up to the top of the tank also? the only lines I would run where they enter and exit on the bottom of the tank would be for a closed loop otherwise you will still run the risk of floods.

There is a huge difference in price between the panworld and the Iwaki, im wondering if it's worth it. If i ran the return lines high up they would just look unsightly is the main reason. Down low they will be hidden well.

[thor109]

That's what I was talking about, the noise from water rushing through the overflow. The wider the overflow you have the quieter it will be.

[567234ta]

That's what I was talking about, the noise from water rushing through the overflow. The wider the overflow you have the quieter it will be.

That is basically a 2" pipe. I think the only way i can have it not backflow would be to put my sump up higher where the water levels are close to the same.
Even if i ran a small tube from the return line up the overflow and out the side of it at the top to suck air once the water got down to it, gravity would still push the water thru the line.