If I build a rock wall 10" high around my pond, scaffolded so that frogs cant get in and out, will the blocked view hide the location of the pond from frogs that wander off and whish to return - or: do then know by sound and memory, sufficiently? From a frog's view, you cant see the pond's surface. Also, would 120 gallons of unfrozen pond water in winter be sufficient, with a general airstone, for 20 4" green frogs? How many?

Most frogs can hop or climb a 10" wall. They use past experience and the sound of water to find ponds and other water sources. You may need a barrier twice as high.

If you mean that after parts of the pond have frozen, there is 120 gallons left that is well aerated, then that could hold half a dozen frogs with no problem and maybe up to a dozen. Get up to 20 frogs, and I would expect problems due to lack of room (they'd be on top of each other) and oxygen. Despite my having literally 300 mature green frog tadpoles at any time, I never have that many adult frogs around. Many get eaten. Many move.

1. Isnt it that the more water, the less oxygen availible as supplied by the limited output dispensed and spread out from the air stone.


2. I have the wall for looks - 10" - i dont think i will put a fence to keep them in, but i might if they dont stay - so, it doesnt matter that the wall is blocking the view of the pond? the pickerels and other frogs will find the pond without seeing it.

While it's true that any oxygen produced by an air stone when dissipated over a larger volume will yield a smaller percentage increase in overall oxygen levels, any extra volume of water will be able to hold more oxygen than a smaller amount of water. Let me try to explain. I'm not sure of the natural levels of oxygen present so I'll make them up using the metric system for ease of made-up calculations. If you have 100 liters that naturally holds 100 ppm of oxygen all by itself, that means that there is a total of 10 g of oxygen in that 100 L. If you only had 50 L with 100 ppm, then there'd be 5 g of oxygen. Now, let's say that adding any air stone increases those ppm concentration values by 20% in 50 L but only 15% in 100 L since it has more volume to deal with (the reason it's not half is that you reach supersaturation at some point, and the water can't take any more oxygen). That would give these results:
100 L pond - 115 ppm oxygen or 11.5 g oxygen
50 L pond - 120 ppm oxygen or 6 g oxygen

Now, see the concentration may be less in the bigger pond but the OVERALL oxygen content of the water is higher in the larger pond. That allows the pond to support almost twice the oxygen usage in an emergency (if the pond seals off). If your aerator fails, then the animals in the larger pond will half a much greater chance of survival. Plus, you're talking about twice the room!!

Frogs have a sense for where water is. If there's any water movement, they'll hear it. Even my still ponds attract them so they just know they're there!