Put salt in the pool yesterday to start using the SWCG for the season. When the pump is running at full speed of 3440 I get all green lights. Once the the pump slows down to my run speed of 2250 I get a red flow light. I upped it up the quick clean speed of 2750 and still red light. Last year I had no issues even when running at my lower speed of 1750. Could the the unit be clogged with anything? When the pool was closed last fall it was also descaled with acid, or at least the company said they did. I cannot get the unit off to check and see as one of the ends is screwed on so I tight it won't budge. It took a lot of strength to get the end off that I did as that side was stuck pretty well too. What tool can I use to try and get it unscrewed with? I am afraid of damaging the plastic end cap.