Backyard Aquaponics
A place to discuss aquaponics

Not pumping at night (until air warms in the AM) works if the O2 stays up and the ammonia stays down.

Your heat loss will be greatest through any wet surfaces. I did a rough test and found it to have an R-value of close to 1/8: that is about four times as much loss as you would get from a dry surface: with zero insulation you still get a thin layer of air that insulates, but water just loses heat really fast due to evaporation.

Thanks, hydro.

A thought for Winter planting... Would it be worth the effort to lay a 4x8 sheet of 3/4" styrofoam on top of the bed and punch holes to plant through? Seems it would reduce heat loss while allowing for plants to grow... Thoughts?

CB

Maybe, but I wonder about the interference with O2 exchange.

As far as heat gain, I installed a reflective panel to the north of my growbed and laid down some glass on the gravel to make a sort of solar water heater one year. This year I didn't bother with the glass (or the tilapia), but it still gave the plants far more light in winter. I'll take them down in another month or two.

I would guess this isn't an issue... The air flow over the roots as it is drawn in by receding water might actually be better!

____________

Got a lot done today with the help of my three younger boys.

We put 500 spore plugs into several logs for shiitake, maitake, blue oyster, elm oyster and lion's mane mushrooms. Also got a post in the ground at the end of one grape arbor that needed to be done... A few other odds and ends like putting the tent away where they had been sleeping outdoors the last few days. (Raining this evening...)

But, y'all don't care about that stuff...

Today we built the long awaited NFT rack over the sump tank. Also put wicks in 80 3" net pots in anticipation of the arrival of 75 strawberry plants...

The rack is composed of eight sections of 4" x 8' pvc pipe with a header manifold on one side and drain stand pipes (1/2" threaded male adapters screwed into the underside) near the other end. Ends of pipes are siliconed with test plugs and few end caps... (The test caps were 35¢ each instead of the more exorbitant $2.29 per end cap, but since we took ALL the test caps Home Depot had, we had to settle for a few end caps to finish the project.)

Pics:





The one downside is that the drill/holesaw combo beat the cr@p outta me!! The saw was so sharp that it would grab easily and spin the high torque drill. About broke my arm a couple times and left me with a couple nasty bruises and scuffed knuckles!! Just glad that job is OVER!!

Plants are growing, but with the next moon phase (or so I have been told) the whole shebang ought to really take off. Nitrates are 10+ and the fish are tiny and barely eating!! Cool weather and 70º water temps have kept their appetite at bay, but the tides will turn soon!!

Barrelponic growth as of today:



More plant growth pics in the next post...

CB

And a few pics of current plant growth...







CB

Thanks for the warm welcome, CB.

I've been following your thread for several weeks now and find your GH/AP system to be a thing of envy. Because I'm more inclined to the DIY approach I'm watching with interest to see how your GBs hold-up over time. I know you've moved towards using barrels these days (can't beat free), but your GBs look... awesome.

Question regarding your GH and the buried thermal mass, how much water/ GH area do you have? Is it your intention to be able to keep tilapia through the winter? I'm curious to see how much a given TM buffers the winter temperatures.

Looking forward to a nice grow season from your system,

-david

Thanks David.

I do plan to keep tilapia through the Winter, but that is subject to change...

Currently, with 2400 sq. ft., I have about 2200 gallons of water and 20 tonnes of gravel (mostly in the floor.) My plan for late Summer and early Fall is to complete a solar water heater on the South side of the GH with a pex heat exchanger in the main FT. Another option is to add more TM with additional barrels of water in choice spots to gain heat from the sun... Ultimately, I want the whole thing off grid, but that is a bigger leap as I solve problems.

When the sides are ON the GH, she holds heat very well. I took them off and then got this cold snap and I am a little concerned... Might put some temporary sides on after work today to get me through mid-next week. I think the tank temps will easily stay above 60 over the next four days, but it took a while to get to 75 and I hate to start over... Still pondering the exchange and other possible temporary means that are not too expensive...

CB

Thinking a head...

Here is a simple thermo-siphon water heater/chiller that I have been pondering...

The idea is a continuous length of black water pipe in the rafter of the GH with both ends submerged in the fish tank. One end has a filter covering it to prevent fingerlings from exploring the heights of the GH... and the other has a strong little impeller pump and valve on it.

My experience is that water can flow past the blade on the pump when shut off, so the idea is to use the pump to charge the line while keeping both ends of the pipe and the valve submerged, then, the pump can be cut off while the water will very slowly thermo siphon through the line to heat (day-time/Winter use) or cool (night-time/Summer) the tank temps. During hours that you do NOT want it operating, once the line is charged, you simply turn the valve off to prevent any water flow.

(One side thought, I have considered adding another valve in the line to remain submerged as well, but pulled out of the tank to siphon/drain any water at an unwanted temp range at the beginning of a heating/cooling period. Ex. If you want to heat the water, but the pipe has been shut off all night, then the water in the line will be cool as the late evening air. Draining it over the side of the tank while pulling water from the tank will accelerate the temp change without having to overcome whatever temp gain/loss was in the line originally.)

Thoughts?

(Illustration for those of us who need pics more than words... LOL!)


CB

Okay... no thoughts or input, so, with me being the impatient person I am (or so my wife says.... ) , I decided to proceed with a little experiment...

Picked up all the parts, minus the pump (had a small one on hand) for a 100' test pipe and the total was about $35. Pretty cheap...

Assembled it and charged the line early this morning and in no time, the pipe was very warm. After several hours I was not seeing as much water siphon/movement as I had hoped, so I slightly modified the plan... With the pump still hooked up, I plugged in a $16 timer that I programmed to run for 5 minutes (more than enough to clear the line) and stay off for 25 minutes which I guesstimated was enough to heat the pipe back up. The cycles only happen between 10 a.m. and 5:30 p.m. to capture the warmest part of the day.

I suspect that thermo-siphon would work better if the pipe were shorter and the ends were at marked differences in height in the tank to take advantage of temperature differences.

As it works now, it was spitting out warm water every 30 minutes and would be more effective with a 400' run attached to the same set-up... Pretty sure the same setup could be altered to cool the tank in mid-Summer just by changing the cycle times on the timer to evening/early morning hours (and maybe running the pipe through a very nearby wooded area....).

So, 1/2" pipe is pretty efficient due to surface area in contact with water... A 100' section will hold a little more than a gallon or near 5l... Not much in a 2200 gallon system like mine, but the cumulative gains with it cycling 15-16 times a day will add up. Switching to a 400' pipe would be significant for even my system. Smaller systems in a GH, or systems that have a glassed solar collector that cycle a number of times a day might see see big gains to extend warm or cool water seasons to grow a preferred fish...

Could also bump up to a 3/4" pipe for more volume, but might increase the heat time/cycle time to one hour intervals... (3/4" x 400' = about 9 gallons of water in the 120-130º range x 10 cycles a day would be nice!)

Input? Thoughts?

CB

Hey, CB!

Interesting stuff. I think that a thermosiphon will only warm a tank if the tank is above it, but could be rigged to cool a tank below it. The pump idea should do it, though.

Keep it up!

So.... the fact that I forgot to shut off the valve last night and the pipes being in the rafters worked against me??!!

You may be right, but I was under the impression that the temp differences at the ends of the pipe determined the siphon flow... Hmmm. Have to read/research more. I want to eventually have a grid free system of regulating tank temps.

I realized that this morning, but don't think it had even a minor effect overnight... The morning tank temp was 72º F and evening temp will likely be in the 76-78º range... Less than a week ago morning temps were 66º, so I'm happy with it in the feeding window for tilapia.... Another week should see 80º, then the game will change to 'regulate temps' vs. increase/decrease temps... LOL!


A question on a different topic: I had a monster algal bloom a couple weeks ago, then it pretty suddenly went away when I shaded the tank and I could see the bottom through nearly 2m of water. MOST of the tank is covered, but there is a small section that still gets direct light and lately the algae has come back along with a slightly higher ph of about 7.4/6. I assume my options are to further shade that spot and reduce feed to the fish. Is that right, or will the tilapia, as they become more active, eat the algae?

The ph, at the time the water cleared up dropped to a low 6 and I buffered it back up to the low 7s with oyster shell grit before the recent bloom...

Thoughts?

Everything else is doing GREAT. plants are growing. Seeds coming up. Some tomatoes and cukes are blooming... Looks great.

CB

why not have the thermo-siphon snake throw a black tub, with the lid on, in full sun...like a car, it will heat way up.
i like the idea, i my do the same for a winter set up...even in palm springs it gets to cold some times

but what about the nightime? if your water get too cold the tilapia may die...def wont be growing...

A thermosiphon works if, for some reason, the water in one side of the U (either way up!) is denser than that on the other side. If you have a mile of coils of hot water on one side and ten feet of the same temp on the other, nothing will move. If you have a fish tank and are heating one side of the arch of tubing, the water will push up and into the other side until average densities balance out.

Algae: I expect tilapia will eat it. That's how they raise them in many places: just fertilize the water and let them eat the algae.

This AP stuff is TOUGH! The last few days I've had little to do as I watch plants grow... Today was a typical afternoon after work... Warm in the GH, so after my tour/perusal, I flopped in a chair with a cold one and closed my eyes listening to the water run... Mmmmm... nice!! Almost fell asleep!

I could get used to this... but it will be tough!

Everything is really coming along. Plants are booming. The barrelponic system especially!! May take a few pics and post later.

CB

Especially tough on a cold sunny winter day when the greenhouse gets up to about 80degF and you can just sit and smell the green stuff growing. *grin*