On 10/12/2015 3:48 AM, mike wrote:

Suggestions...
Change the subject line to better describe what this thread has turned
into.
Describe better what you're doing with the fish and what you're growing.

We work towards having an urban farm, so one of the things we're doing
is raising our own fish to consume.

Once the fish leave your premises, all manner of liability issues arise.
Food laws and regulations are not always intuitive.

We can't sell the fish dressed out, but we can sell them live. IOW,
someone can come and bring a bucket, dip out their fish, and take it
home and dress it out themselves. The fish is part of an aquaponics set
up. We pump the fish water into grow beds which help consume and filter
out the fish waste. That water is sent to a sump tank with small baby
fish in it and waste eating critters like crawdads and catfish. Then
that water is sent through a large barrel filter, and then drains back
into the main fish tank. The initial system we set up was small, but it
has grown as the fish grew to adulthood. Now, we have large tilapia and
our son is planning a fall fish fry for him and his buddies. Each adult
fish is at least 9 pounds +/- undressed.

Grow something with high profit margin, like weed.
That significantly lessens your need to minimize heat loss.
Consume some of the product and you'll be significantly less
motivated to fix anything. ;-)

When we get the new green house finished, we're hoping to grow fresh
food we can consume ourselves in the winter time. Eventually, we'll
tweak it to possibly sell crops like lettuce.

DO THE MATH. Find out where the heat is going. Fix the biggest issues.
There's no need to optimize the small stuff if you've ignored the low
hanging fruit.

The biggest issue is heating in the winter time, and venting extra day
time heat while at the same time having passive heat sources to keep it
warm at night.

Right now, you're getting random inputs from people who have to make
assumptions and guesses about what you're doing. Throw some pictures
on a sharing site.

I'll have to take some new photos. Everything I've taken thus far is of
the old set-up. We moved the big fish to a 900 gallon tank that's been
outside of the green house for spring-summer-fall. We'll break down that
tank and move them inside when the night temps get too cold. I may just
take a short video with my phone and upload that.

I find the project fascinating, but I have nothing better to do ;-)

It's a hobby, so far, anyway!

--
Maggie