Originally Posted by
Coastie5685
http:///forum/post/2957922
now trying to figure out a ovreflow.. i have a marineland hob filter that i use for the freshwater tank. its rated at 200gph.. if i drill a hole into the bottom of the filter and run plumbing straight down.
then have the return pump be a maxi jet 1200 rated at 295gph? no? how does the OF ratio to return pump go? does the return have to be less gph then overflow?
I haven't done this, but the idea interests me. But, on my hang on back filters, if the power goes out and the water level in the tank is low, most of the the water siphons back into the tank. This leaves the water level in the filter below the impeller and prevents it from starting back up automatically once the power goes back on.
To put a bulkhead in the bottom of the hang on back and drain down to the sump/refugium, you would have to size it so that it never got ahead of the water that the impeller is pulling from the tank. This in itself isn't a huge problem because any surplus would flow back into the tank as designed by the original HOB design. If the power did go out, the remaining water would drain down the bulkhead and it would never automatically restart when power came back on.
But your return pump certainly would restart, which would probably overflow your display tank and cause your return pump to blow microbubbles and possibly burn up.
I think that you could probably balance the return flow with a ball valve to make the system work, but it might shorten the life of a return pump, and
a power failure would result in 30 gallons of water in a 20 gallon tank.