Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
2 x 90* is OK, but if you can make it work with 45* fittings that is closer to a long sweep and is better than standard 90* fittings. It has been tested. They set up 3 similar plumbing set ups except one set up had standard 90* fittings. The other set up had 2 x 45* fittings where each 90* was. The 3rd had long bend 90* fittings. The best flow was the long bend 90* fittings. It is more like a 1/4 circle, not a tight corner. There was also much better flow from the plumbing with the 45* fittings. Not quite as good as the long bend set up, but close. Makes it well worth using 45* fittings if that is an option.
I regularly add PVC fittings to the intake side of HOB and canister filters and do not have problems because of that. They work just fine.