Yes I keep spelling it wrong. A lot of people soak the food in it and feed it to the tank. Using selcon on a regular basis is said to increase the amount of vermetid snails in the tank.
If it retracts and brings particles in from the water I dont think it is anthing that is happening becuase of the zoa's. It is probably a tube worm or a vermetid snail that is living underneath the zoas or in a crack of the rock. Do you feed your food with selcom?
you can get a booster pump for the ro system, that will boost your pressure and ro water making capabilies if you lack water pressure.
best prices on ro/di systems are from www.purewaterclub.com