I think it sounds/looks like a good idea, especially if you were using them in a gravity situation as you proposed ..... I didn't look into where a person might get them or what the prices are (maybe you can post a link for us), but it surely adds a lot of oxy to the water, I'm impressed! That said, I would think that they would lose a lot more to evaporation , so you would have to be adding water all the time ...... since you are using a pump to get the water to the growbeds, I don't see any additional expense in energy this way (gravity fed), but having to constantly add water would be my problem with it. One other thought is, if it were gravity fed, I don't think the water would be quite as vigorously stirred, therefore, possibly the airstones would cancel out any advantage of the flowforms ...... I guess you'd have to test it to make sure
Right now I'm adding 10-15 gallons a week with my siphon system in a 50 gallon rubbermaid FT and a 5-10 gallon "growbed" which has nothing but a couple of tomato plants and some small Guppies that managed to get pumped up there as fry. I have to drive 65 miles to get decent water as it is, so I don't think this system would work for me, but I'd like to see what others have as input for this type of aeration before I close the door to something like this. Thanks for the vid