bubbles and foam

Question

Hello,
I have a 200G fresh water tank with 40G Sump.  All discus fish that I feed with frozen blood worms from a Hikari.  I've had the tank for 1.5 years now and change 40% of the water every to weeks.  I place 1 Tbs of salt per 5 gallons and only add water conditioner.  Now for the problem.  Recently when the water flows below to the sump there is a lot of foam/bubble build-up in the sump and it overflows.  I've never had this issue before and have not changes brands of salt or conditioner.  If I change out 80% of the water it goes away but after about 1 week it foams up again.  What's causing this?  What can I do?  I'm thinking a protein skimmer might help but I don't know.
thanks
-john

Answer
Hi Johnny,
Foam is a sign of high bacteria levels.
Blood worms can cause this over time, and really, the fish should have a more varied diet. Blood worms once a week. There are other frozen or freeze dried foods they can eat.
I would do no more than 50% water changes, but they need to be done on a weekly basis.
I would also add a Bio Wheel filter like the Penguin.
Feed only once a day also.

That should solve the issue!