ok ive done my plan for a rack system with mutiple tanks running the same water through all tanks and a massive sump now the idea i had was that there wouldnt be any protection on inlets and drop tubes until the water gets to the final tank before the sump then large sponge, idea being that the fry will eventually make there way to the final tank (wont have any breeders in there) then they can feed on the bit and pieces that get stuck on the large filter pad until i can suck em up with a small syphon and transfer into my large grow out tank, grow out tank uses same water as breeding sections so no problem with water quality change or anything the only thing i thought off after doing all my designs and plans (hours of work ) was the effect on fry of dropping down verticle tubes with the water flow running at fair rate are they gonna be hardy enough to handle it? or is it likly to shock them to death? trying to be innovative and minimise my time catch fry and moving around stuff in tanks. gap for water intake will only be half a cm and thus the fry will automatically migrate to the tube due to it being a good hiding spot and the water flow will suck them down. have sucked plenty of fry down my syphon tube out into the garden and i think they have survived when put back in the tank but might be older than ones that first emerge from the cave the other option ive considered is slow incline method of circling flexible tubing that would reduce speed of flow like a fish ladder (if you know what i mean),
heres a crappy diagram i drew

I think the fry will experence a high mortality rate going through the pipe work. For example, there is a 98% fry mortality rate going under weirs on rivers because of the huge changes in pressure damaging the internal organs. I dont even syphon fry any more because of the issues faced with fry getting damaged in the syphon tube or the spash out of the bottom. Their underbellys are extremely sensitive and any sort of splashing onto it will damage them, often beyond repair.

I like the idea, but unfortuantly i think there will be issues. It wont kill them all, there will be some that survive, but im not sure what the ratio would be of survivers. It might be high enough that you are ok with it, it might not be.

I too got annoyed at having to catch the fry out of the breeding tanks and transfering them to the grow out tank. So i changed my plan. I built a large fry saver out of a tupperware container which is big enough to take a cave with plenty of room to spare. When i have a male on eggs i will carefully take the cave out of the breeding tank and put it in the fry saver in the grow out tank. I too use the same water so there is no issues there but i always do a test anyway, just to check for ammonia and nitrate mainly. Once the fry are out of the cave i wait for about 2 weeks then let them go into the grow out tank while i take the male and cave back to his breeding tank. Works well so far. only issue i have found is having multiple spawns at once. I dont want to have two caves in the fry saver at once as this will most likely have issues so every now and again i have some that stay in the tank with mum and dad as the fry saver is already in use.

doing it this way save lots of time in catching fry and the stress of transfuring young fry around. when they are eggs they are totally oblivious and most of my males are experenced enough that they dont mine the slight wobbles (of course i do it really slowly and gently).

have you thought of making another fry saver so have two seperate one in growout tank

i was thinking of putting cave strait into growout tank when dad on eggs what do you think is it a bad idea