sump question + skimmer question

[Matt]

Hi,
I've got a 37g semi-cube (from Nemain) that I'm setting up. It has a rubbermaid sump plumbed under, and it's my first time with such.

Question 1: It has been drilled high on the centre-back, and has an acrylic overflow constructed around it. It has a standpipe plumbed outside the tank that is open (full draw) and if the water pump is allowed to pump enough water to fill the overflow past the drain (where it would start to need to take air from the standpipe), it gets very noisy, and if I restrict the airflow then, it gurgles and flushes. ARGH. Anyone good at this stuff that would like to help? It is relatively silent when the standpipe has a rag stuffed into it and the pump is restricted to not going very fast.

Question 2: I have also got a Precision Marine CV 426 skimmer, that has a broken fitting. It is the fitting about halfway up the side, and is labelled ORBIT 3/4" x 1/2" x 6" (although it nowhere near 6" long, more like 1.5"). Anyone have any idea where to find this part? Home Despot has 3/4-1/2 fittings, but the threads are finer and won't work, IMO.

Regards,
Matthew