Seems like Aquarium waterfalls would be great for ~ 70g rez. They pull water from near the bottom up through a cleanable filter then cascade over a built in ledge. So the water is circulating plus the surface is getting oxygenated . ~ $40 for a' large' one
It is very interesting what I've been reading about areation in water. Not what I thought and seemingly not what others thought either. Inject air to provide lift. DOing happens over a large surface.
The big player here is waste water treatment. They have to maintain max DO and cheap on millions of gals. And I have noticed over the years the treatment has gone to a different look. No more splashing down ladder falls. No more fountains of spray. Just flooming.
And so I had to look at the science and those air stones are not doing what we think. Sorry. Many will not buy this. It is OK. It is deep, and has to do the with the molecule sizes vs the surface area.
But, it is simply this. The bubbles from the stones don't do anything directly but lift water.
1- it is a hot air bubble. And we know this needs cold water to DO saturation
2- a bubble is too small a surface. Many tiny, hot surfaces won't work.
3- the stone lifts water from the bottom to expose it to the surface of the vessel ONLY.
4- even the smallest pump will lift 100 times more water than bubbles can.
This has been know in aquarium keeping for a while now. Flooming.
I have some test kits on the way and if I get max DO then I will only floom.
That is 10 gal in a bubble foiled tote. Eco-185 with no fitting, just pump to the surface.
This is a typical areation pond these days, no hot air, no fountains or falls. Just pumping.