Backyard Aquaponics
A place to discuss aquaponics

I've got to agree with Axl, but only if it is a homegrown one! Those store bought ones are only cheap (HA!) imitations of the real things.

Kevin

My tomato outside is almost ripe. whohoo! And my girls counted another 22 tomatoes. It appears that even though the greenhouse gets cold at night, the warm water flowing through the growbeds is keeping the plants happy.
I'm thinking that the continuous flow idea isn't so good -- at least for plants that will be in the GB for a while. My GB's are so choked with roots that the water level stays close to the top all the time. And my wife is complaining about a nasty smell. I'm guessing I'm getting some anaerobic zones. So I bought a couple of timers and I'll be trying those out in the next few days.

Progress is slow on the greenhouse but I'm still hoping to have it up by this fall. I've been cleaning junk out of my garage and getting ready for a big push. Two of my Tilapia are getting almost big enough to eat -- maybe 8" long and I'm guessing at least 1/2 lb. Not bad for a 70 gal aquarium in a basement.....

Sounds great! Fish and tomatoes, yum!

I've noticed that sometimes the greenhouses producing plants using conventional methods have an odor about them as well. Part of that can be due to molds/mildew occurring. Just watch for any green or black areas on any surfaces in your GH.

Kevin

as Kevin says....I opened up my GH more and it made a big difference with more fresh air being able to enter...disadvantage is that it gets cooler in winter but being in the subtropics that isn't a major concern for me

If the roots are choking the growbeds they must be growing well
I don`t think the plants mind cold airtemps as long as the roots are warm.

A very general rule of thumb for ventilation is upto 3 complete airchanges per "minute" in summer and 2 airchanges per "hour" in winter.
Keep plodding on with the gh and it`ll be done before you know it

just getting my GH air pumps work'n

The roots are definitely choking the growbeds. I suspect I could dump out my grow bed without a single clay ball falling out of the "brick"

As far as ventilation: 3 airchanges per minute requires an expensive and noisy fan -- that is why I'm pursuing the bubble system -- Theoretically I can simply pump water in between the layers of plastic to cool the air in the greenhouse ( and at the same time, collect heat for the nights) If the big solar collector does not provide enough cooling, I can turn on the bubbles for 50% shade..... Then I'd only need to change the air to replenish the CO2 the plants are using up. Perhaps the fish will generate enough CO2. Unfortunately, the extra complexity makes the greenhouse take longer and cost more to build.

Yup, that is the bite! Which route do you take in order to get the results you want? You'll get it sorted out, but until then to the drawing board and the calculator!
Kevin

Passive ventilation doesn`t have any running costs.
The vent size can be calculated to get the required airflow per minute.
All you need is as much height between inlet and outlet vents as you can manage and a temperature difference to drive it

True, but if you want to close the vents, it can get expensive. I have seen greenhouses where the whole roof hinges open -- or rolls upen -- but those systems cost money and have operating costs -- and probably maintenance issues -- possibly leakage issues.

Leaky vents become a big issue when the outside air is below freezing -- the temperature difference drives a lot of air through a small opening.

Joel, Have you looked at the website for Northern Tool? I think they carry a couple of different models of solar powered attic vents. One of them was fairly cheap (around the c note mark, IF I remember correctly). I know Harbor Freight also carries a solar powered vent fan for thier Poly Carb kit Greenhouses, but it was a little more expensive. I think Farmtek and Charley's also have them.
Kevin

Thanks for the tip, Kevin, I've pretty much decided to count on the bubbles for cooling and just use a small louvered fan for exhaust/fresh air. Any vent large enough to make a difference on a 20 x 66' greenhouse is going to cost money and/or leak badly.

On a positive note, I ate my first AP tomato. My little boy saw it hiding under the leaves, snatched it and then threw it on the ground when I tried to get it from him. It got bruised a little but was still very good. I told my wife it was a $1000 tomato -- she said, "More like $20,000!"

I've gotten tired of feeding my Oscars beef heart and chunks of scrambled eggs so I bought some feeder goldfish -- The Oscars don't even seem interested. Perhaps the water is too cold -- or maybe they are afraid of live food.

Despite the intense heat this weekend (80+F) I managed to assemble 12 more arches for the big greenhouse. And I filled up my modified freezer (I cut a hole in the front and glued in a piece of plexiglas) with water and threw some fish inside -- unfortunately, the window leaks a bit -- perhaps biofilm will plug the holes.

Last night when I got home from work, my Tilapia were not greeting me at the glass begging for food. I got worried. I had just installed a digital timer that would run for 15 minutes on a 2 hour cycle. I tested the water and I got a very low reading of nitrates and detectable amounts of ammonia and nitrites. pH was about 6.8 or 7.
I'm guessing that the water isn't circulating enough through the GB's to convert the bad stuff into nitrates. I increased the cycle to 90 minutes on 30 off. I added an airstone to the fish tank and I'm going to cut back on the feedings (it is so hard to resist their cute little faces begging for food though...) I'll test tonight and see what the chemistry of the water looks like.

Tilapia taking a pass on food is a sure sign of water quality issues. Good diagnosis. Watch them carefully and increase your cycling again if needed.

I measured the water chemistry last night and everything was back to barely detectable -- even the nitrates.

fish are hungry again.