Maintaining a Pool Without a filter

[Woraner]

I have three 5000 gallon water systems that I want to be cleaned and treated like pools but I don't have a proper filtration system.

I just recently opened a miniature golf course in south Florida and while it was in construction I was told by the contractor that there would be no need for filters and that the ponds would be fine and self sustaining. Being a pool owner I should have known better. Now that construction is done and I have been in business for over a year, I can't add filter because the cost would be well over $40,000 for all the parts and the construction to add the piping.

I have 3 algae filled ponds that have constant flowing water 14 hours a day. I try my best to load them with chlorine but that doesn't seem to do much. Is there anything special I should be doing? does anyone know of any vacuum product that filters algae or a good portable filter?