problems with overflow...

[invertical]

I can't seem to get a good siphon from my internal box to my outside box..I have a 1" pvc tube that barely siphons at all, and I don't know if it's the angle or not....I have a rubber hose that barely siphons as well 3/4" ID. and the ones that seem to siphon the best, but not nearly enough water are the 2 clear 5/8" ID hoses...if I put the 3/4" ID hose in with the two 5/8" ID hoses it siphons decent, but not near what I feel just the 3/4" ID hose should be doing along....also does the PVC tube have a bad shape for a siphon tube? any help would be great!!! I can't think of a reason why there would be poor siphon....I mean it could fill up a quart jar in about a half an hour...with the pump on....I have to turn the pump waaaaay back in order for the pump chamber not to run dry.....please help i'm getting sick and tired of this overflow!!!

the setup:
Attachment 207769
Inside of exterior box:
Attachment 207770

 

[reefraff]

That thing look bizarre, started off life as a magnum HOB filter? and it isn't going to hold a siphon if your return pump shuts off.. you should have a U shaped tube that will run water through pretty fast. Vinyl hose isn't a good substitute because it pinches closed when it bends. You should REALLY buy a new overflow. Lifereef and ADHI both make good units.