sump flow - HOB overflow capacity

[Osaka-san]

I just got a new sump up and running and I am not satisified w/ the flow I am getting. My tank isnt drilled so I had to use a HOB overflow. The one I have has a 1" bulkhead fitting at the bottom which I understand limits flow to about 600 GPH. My return pump is an older Little Giant 4 series which should have about 800 GPH at the tank. The problem is that I have to throttle the return line a lot to balance the flow which makes me think I'm not getting 600 GPH in the return. I fabbricated a stockman style stand pipe to help with noise and although I am not completely happy with it (I made the vent too large so it's noisier than it should be) I believe it it is not limiting the flow - it iis made of 1.25" Sch 40 PVC so its ID is slightly larger than the bulkhead. I am currently using two 1.25" U tubes to feed the overflow plenum so that is not the limit. I do not have a flow meter. But I do have two measures of flow - perceived, by sticking my hand in front of the nozzels and the clock position of the ball valve. The flow into the tank is channeled thru a SCWD and exits one at a time thru two seperate Loc-line nozzels with a flat narrow opening. If I had to guess from flow pressure it is less than that the fluval 305 I have running which is rated at 185 GPH. The ball valve is at approximately 45 degrees, another indicator that the flow far less than 600 GPH and. While the calculation is too complicated for my feble brain, I can approximate the area of the ball valve at 45 degrees and ratio it to the area at full open as.approximately 50% - as only one axis is collapsing. That would indicate that return flow is 400 GPH or less - well below optimum. Any thoughts?
:?:
Another item - regarding my return pump - it is hot to the touch. Pretty hot in fact - I'd guess 50C or so - it wont burn you but it isnt comfortable to hold on to. Is this normal? Its rated at about 150W which if you think about holding a 150W light bulb in your hand - it would actually be too hot to hold so maybe this is OK? seems to run well. I rebuilt the pump side and lued the bearings w/ non-detergent 30W as specified.

 

[scubabum1983]

two things I had a sqwd and it restricted the heck out of the pump and made huge amounts of back pressure. two by splitting the flow to two seperate returns off the sqwd it reduces the flow further by having to push the water in two directions down more hose or pipe, longer distance, more flow reduction. I have an older little giant you can have to play with and see what you think and see if its the pump as well. also break down and drill the tank already. it isnt too difficult. I drilled mine with a drill guide bought at sears, plumbers putty and a diamond bit.

 

[Osaka-san]

Little Giant

Little Giant

Hey thanks for the offer. I'd really like to check the pump out. PM me on how to meet up w/ you.
My tank is a fluval Osaka and is tempered on the bottom so no drilling there. Annother problem is, I have a reasonable ammount of fish and coral already installed. I am lothe to break it all down to drill. I wish I had done so originally - I've now done eight 45mm holes in two sumps w/o a break so I agree that it isnt too hard. Any way to drill a tank "sideways"? LMK and thanks again for the offer.