Backyard Aquaponics
A place to discuss aquaponics

I want to have a system that is not a loop, I have a 5500 gallon tank, and I would like a high stocking density of rainbow trout to sell to my local grocery store, I have a well also. My Idea was to have a system where the water as it warms up is changed out for cold well water and the excess water to water my plants that are in the ground?
Do they make such a thing to change out water automatically based off of temperature or will I have to do it manually? What are stocking rates for rainbow trout? How fast do they grow? How much would it cost per fish to raise to "market size"?

That is a big fish tank! You could do a lot with it.
Most trout farms are located next to fresh water sources rivers stream etc.
They divert the fresh flowing water. Run it through tanks or raceways and then return it to the river. Trout like cold water so think around a constant 12*c
You also need to get rid of fish waste. I am guessing but say 10% of you pond water per hour. It will vary depending on your stocking density but take that as an average. Disposing of 500+ galls of water per hour would require a lot of thirsty plants. Returning it to the well. Well let’s just say not a good idea.
If you have the space to build the growbeds for filtration you could raise a lot of trout it that pool.
There are one or two people on here with V large pools. Have a read of their threads. I warn you. It’s addictive

Clearly you can simply measure.temperature, and switch on a pump..
But there would seem to be Many Other issues to consider..

Eg. What condition is the Well Water in..
How are you going to treat the nitrogen products and their build up.. temperature, pH, turbidity, oxygen, etc. Etc.

I suspect that if you have to ask such a general series of questions, then you have not done much research about the fish themselves ..

As suggested, a true commercial system has near.constant.water replacement ..

Hang around and read discussions on problems and you may.start to realise some of the complexities of what you seek..
..
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Buy a text book on aquaculture like Timmons et al. "Recirculating Aquaculture" or LeKang "Aquaculture Engineering"

At the very least download all the SRAC articles on aquaculture in general and trout in particular.

Then come back to us if you want further commercial help.

The water would be used to water lots of zucchini i'd say 1/2 acres an the rest could water my field? Would that work? I did a lot of research 6 months ago and then decided to wait a year so I basically forgot everything I read.

If I had a Bio filter would that work? I wonder what it would cost to run a pump 24/7 or Hour on Hour off?

"Clearly you can simply measure.temperature, and switch on a pump.." Sorry I should have specified I cannot be there all day, how long would that much water take to warm up a few degrees?

The reason why Stu recommends reading up on the books is that plain Aquaculture can be a high risk venture for those that are properly trained, let alone not trained. Without proper training, checks, water quality testing, you can end up with a lot of dead fish very quickly, and more likely after months and months of growth.

And for a beginner without any proper training to have a high density of trout, it's a recipe for disaster.

To answer your other questions, there are way too many variables, what pump are you using? What's the head on what you're pumping? How are you planning on heating the water? Why are you heating the water with trout?