Backyard Aquaponics
A place to discuss aquaponics

Well, I spent two days trying to find a gravel pit that wasn't frozen and a trucker who would haul it. The pea gravel they had to offer was full of sand. Coarse sand -- he said it was 3/8" to #8 screens.
I opted for 3/8" to 3/4" washed gravel. And then the dump truck got stuck in my driveway and his front wheels slid sideways and almost ran into my house. So now I've got two piles of gravel in my driveway. 20 yards total -- sure doesn't look like much for $490.

So much for saving time. Oh well, it's here now and now I don't have any excuse for delaying rest of the project.

Well you could always wash it where it is.... mind you it might freeze into a mound... or what the heck ... just spread it out for traction and back another truck up over it.... LOL

I'm not going to wash it until it is in the greenhouse -- then it would freeze for sure. I'm not sure I'll even want to wash it -- don't most people add rock dust??? Seems foolish to wash the rock and then dump rock dust in for minerals.

when I started my mini aquarium system, I circulated it for two days into a laundry tub. The water was brown and cloudy -- but overnight, the water cleared up and the particulates settled to the bottom of the tub. The same sort of idea should work for my large system

Here's a quick sketch I drew up of my greenhouse concept. I didn't draw all the pumps and piping, but I'll figure that out as I go.

Oh, I forgot to mention that the gravel grow beds are going to be installed first and will be secured to the wall so they will be ballast to keep my greenhouse from blowing away. 25 tons should do it, eh?

I'll scoop in the gravel with a bobcat before I build the raft tank in the middle. My idea (I can't be the first one to think of this!) is to run the water through the gravel grow beds first to filter out all the solids and then drain into the raft tank.

As I see it, gravel beds seem to deal better with solids. and I didn't want to mess with a filter system that I would have to clean and maintain. I know that the UVI system uses the cleaning of the filter to vary their nutrient levels so I will be sacrificing control for convenience.

But for fast-growing crops such as lettuce, I believe that the raft system will be more efficient and cost-effective -- besides giving me the option of selling a whole lettuce plant, roots and all.

Wow! Drool. Drool. Drool.

I had to jump in on this;)

This is a very exciting build and AP venture. I like the plan and the challenges the region presents to you. I particularly think you are headed in some very, very good directions. Using the gravel beds as filters and channeling runnoff to the middle raft float bed is an excellent design idea.
Effectively you are making the center float bed your sump system, is this correct?

If I may, I see your greatest challenge to do with the size of the fish tank and the fact that it is not designed for aquaculutre. This is perhaps my pet peeve, but bear with me. By this I mean you will have a constant challenge removing solids from this type of tank. You will have to either place several sump pumps at various strategic locations around the bottom of the tank to ensure solids are collected, and even then at high stocking densities there will be pockets untouched. Or you will have to circulate the 6000 gallons into a vortex to round up the solids in the center where a sump pump would suck it all up. On a flat bottom tank of 500 gallons circulating water into a vortex requires a fair amount of energy and I suspect would be moreso for 6000 gallons. If you have the resources perhaps consideration of two or three smaller aquaculture purpose built tanks would make your system more efficient.

Great job and thank you for sharing.....

Mike

Thanks for the input, Michael.

firstly, i'm not going to start with high stocking densities -- I haven't found an affordable fish -- (how many feeder goldfish would it take to make 1/2 lb per gallon)

And I found a fellow who specializes in filtering swimming pools on the net -- he basically uses a 1/2 hp pump to create a circular flow in the tank and that pulls all the solids intot he middle.

I'm still looking for tanks. If I find some, I'll get rid of the swimming pool. Unfortunately, if something isn't used by industry here in Alaska, shipping often costs more than the item. I would think that tanks would be especially so since they take up a lot of room in a shipping container.

yep, that's the plan -- center raft tank will be the sump for the gravel beds. I don't think it will be a huge problem if the level in the sump fluctuates a little. And it may not fluctuate very much -- I'm planning on using autosiphons to drain my growbeds -- and it is very likely that all 12 won't cycle at the same time. I've been posting so I can get feedback from others on my ideas. I consider all criticism constructive. I've been thinking about this system for a long time, but I'd rather work on potential problems before I actually buy (any more) materials and start building.

I'd rather hear "you're going to have problems and here's why" now than "I knew from the beginning that it would never work" later.

Yes those aquaculutre tanks are expensive to source and ship, which is why a great many of us DIY AP'ers don't have them and are sourcing all sorts of fun and interesting tanks...to include soft swimming pools and steel cisterns! I use a 1/3 hp pump on my 500 gallon tank and it gets the solids to the center in about one minute before it cycles off. I suppose if I kept it on continuously the fish would act like salmon trying to swim upstream of a swift current:) Might be fun to watch....lol

I agree with you. The worst thing that could happen using the pool is it does fine with light stocking density. Also I agree your sump will not likely fluctuate hardly at all. Good design. I think many of us are going to be watching you closely regarding the soap bubble insulation.

I've just read some chatter on the solaroof board that bubbles freeze and pop at cold temperatures. So in order to keep the insulation in place, I may need to keep generating bubbles all night at cold temps. That could increase my heat loss and decrease the efficiency of my whole system. (Supposedly the bubbles will stay inflated for up to 6 hours when above freezing so the bubble gen only needs to run twice per night)

One thing we are playing with here is to make your own tank from cinder block. That way you can make it any shape you want and you can either seal it with a safe paint or install a liner. We simply plaster the walls and paint.

Another advantage is that you could make the bottom slope anyway you wanted to concentrate the solids in one place for easy transfer to other parts of the system. A simple poured cement floor would do the trick.

I am not sure how hard or expensive cinder block is in those parts.

This was my concern - at some point in time thay are all going to be flooded and must be taken into consideration

So 4 * 8 * 1 deep GBs works out to about 1,500 gallons of water for the 12 GBs if all flooded, so using a 6,000 gal tank would be large enough to satisfy Murphy

Ems I like the design and I too am looking forward to see how the bubbles work for you

Ems, something that has come across my mind with the solaroof(I watch the forums too) is to add a third layer of poly to the outside of the bubble cavity, and inflate it with air like the traditional quonset inflated greenhouses. This may provide enough insulation to prevent freezing the bubbles, and may only need to be inflated at night.

Q: Is your pool a rigid bottom, or somewhat maleable? if it is soft enough you could form the earth beneath it into a cone to help sweep solids inwards. If it's a rigid plastic perhaps putting hot water into the bottom would soften and weigh down floor into the cone. Then let it cool and drain the plasticky water.

Hayden

Ok SO I have been doing research on what to make a tank out of and I think I have found the best option for developing worlds and Alaska.

Its called ferrocement construction and is really simple and strong

We have 4 water tanks built on the property here made from just chicken wire and a 2.5 or 3 to 1 sand to cement ration (I would add rebar in the middle of the two layers of chicken wire for a fish tank maybe 3/8"). They are about 2.5 - 3 cm thick and they are solid like a rock. (i know we hit one with a car once).

Do some research on the net there is lots of info.

The best part about ferrocemtn is it is mouldable. You can make round square triangle tanks. And it will even work for growbeds. Which is what i want to use it for.