I recently bought a house with a 20x40 in ground pool. The previous owners used Baquacil. The vinyl liner is 10+ years old and in decent shape. The local pool store said that they do not advise changing from Baquacil to chlorine if Baquacil has been used for more than 5 years. Is their recommendation valid? If it is possible, I would like to change to chlorine, but would not do so until next year since I have already lost almost a month of pool time getting it opened.

My current issue is that the pressure in the Hayward Perflex DE filter rises from about 8-10 psi to 20 psi in about 2 back to about 10 psi but then goes back up to 20 psi in about 2 hours again. If I let it continue the flow rate goes to almost nothing. I assume that this is not normal. I did have an algae issue that has been resolved using Alum. I then cleaned the filter with Leslie's DE filter cleaner and spraying the fingers with a hose until they looked clean. I am now at a loss as to what might be causing the problem.

Thank you for any ideas that anyone has.