Do I need to replace both pumps?

Had a energy audit by the electric company. They advised to change to a variable speed pump to save energy. I have two 1 hp pumps one is labeled "clean" and the other is labeled "filter" I run one in the daytime as it runs my solar pool heater. I run the other at night for my in pool cleaning. My pool is a 10,000 gallon play pool. Pool and equipment are approximately 16 years old. When I asked the audit fellow if I had to change both pumps he said no just have it plumbed so one pump can run both clean and filter. Is that correct or do I need to change both pumps to variable speed? It seems to me that the costs would defeat the savings. Any advise would be appreciated. Thanks

I only have one pump.

I would expect for a 10,000 gallon pool you could quite happily run on 1/4hp pump if you don't mind people laughing at your little pump, My pool is a little bigger and you can read from my signature that I am using 0.08hp I don't mind people laughing at my little pump but when they see how little my electricity bill is for the pool they don't laugh anyway they just ask me to re do their pools!