A recirc. skimmer pulls the water for the skimmer pump from the body of the skimmer. It continualy recir's. the water in this chamber. Bulk water for the skimmer is supplied by a seperate feed pump.Being a seperate pump supplies water to the skimmer it can be used external of the sump.The pump that feeds the skimmer can be external or submurged.
A non- recir. the skimmer uses one pump, pulls bulk water into the skimmer and also feeds the body of the skimmer.One pump does the work of two. Non- recir. need to be run internal, so the skimmer pump can be submerged, to draw the water into the skimmer body.
All things being equal, recirc. are a little more efficent and will handle a larger load.
If your currently using a recirc. and the water exiting the skimmer is slowed, could be two likely causes.
1) The feed pump is clogged ,either on suction or output, or valve, if there is one, could be closed, blocked.I'm sure there could be other causes as well, but long and short, not as much water going in as before.
The amount of water entering the skimmer has been reduced.This will result in the level of water in the skimmer body being dropped.
2) The outlet of the skimmer body is restricted. It's clogged, valve clogged, valve closed etc. Something is causing the water not to exit as freely.
This will result in the water in the skimmer body going higher.
Not knowing everything else specific, would be my best guesses.
Hope all the explaination make sense.
Todd
