Wow, that's a large pond! Could you be more precise about what your algae problem is? Pea-soup water, string algae, something else? Do you have pictures? Is there a reason you don't have filtration? even if you don't have fish, those frogs and tadpoles will be contributing waste products that need to be broken down.

Too expensive to put in filtration for such a big pond and since we have no plans for fish hadn't planned on doing so. I thought the beneficial bacteria I'm putting in every 2 weeks is supposed to help break down waste? There is a lot of oxygen being injected in water due to compressor system with 2 outlets plus fountain to keep water moving. There is a mix of pea soup and string algae. I put blue dye in a couple of days ago to try and help the situation so a pic wouldn't show much of anything except dark blue. The pond is about 30' x 40' x 2' deep. Thanks.

Thanks Nil13!

My frog ponds are a lot smaller than yours but I never dump them out and clean them....I don't use any products in them either.

The water is clear. Always has been. There is dirt on the bottom on top of the liner and waterlilies planted right into it. No clue how many gallons. They are small. My goldfish pond is about a thousand gallons. Has been clear for twenty years but I have tons of plants in it too. The only time it turned green is when we cleaned it one year so we stopped doing an annual cleaning. I have five liner ponds.