Laminate schedule verification

About a cubic meter each for growing, same size as yours. But some are rectangular and can hold 3 cu m. All tanks have covers.

 

I suspected you will elevate the tanks. makes it more complicated as the bottom will not be flat. The bottom part of the tank is considered as critical part of the design. Flat bottoms are designed to be placed on a solid surface while tanks with drains have to be supported somewhere where there are strong points.

Just for clarification, when you say Grow Beds, do you mean this is where you place the fingerlings before transfer to a bigger tank?

 

Nice... Yes mine will have a cover as well, going to make it out of treated wood as well. Not too worried if it starts to degrade, I can just make a new one super easy every couple years if I have to.
I am currently designing the plumbing, and realized I made a stupid mistake, I put the tank and grow beds at the same level, so I won't be able to siphon the water from the grow bed into the tank, so I'm going to tweak it a little and make it rectangular so I can lower the water level.

 

No, by grow beds I mean the tank I will fill with expanded clay beads and will grow plants in. It's an aquaculture system mated with a hydroponics system. Pretty neat idea. The fish provide ammonia, and the bacteria in the grow beds turn the ammonia into nitrites, and then into nitrates, and the plants use the nitrates. Pretty efficient filtering system for the fish, and very efficient nutrient system for the plants.

 

The bottom will be perfectly flat. I will be using a bell siphon to regulate water level, so the bottom doesn't have to be angled for a drain, in fact the water will only to about one inch from the bottom, and then start filling. Here is the bottom of the grow bed stands, it's a couple layers of thick plywood, I will just drill through for the pipes.

 

Drewdriver,

I am giving you the laminate schedule which should suffice for your requirement. I am used to Metric so just convert the values and glass weights to English system. Pay attention to reinforcement details. I did not increase the bottom lam because you said it will be perfectly flat with the base.

Mine was laminated with a good ISO gel coat and ISO resin up to surfacing mat then ortho. Last layer is WR for a good finish and to take up the tensile stress. The outside was flowcoated with neutral gray finish. Black is best as it is the most effective color in blocking UV light.

While Vynil Ester resin is standard liner for commercial grade water pipes, it might be an overkill for your use but it is up to you. At most, you can Use VE in the first two layer then ISO resin afterwards. You will probably lose more water from evaporation than leeching through the gelcoat/surfacing mat barrier. Besides the inner layer is not exposed to the sun. It is the outer layer that must be protected.

I have built boats with good grade ISO and it is now 15-16 years with no osmosis or blistering problem. Our Ortho resin molds disintigrate in the sun after several years but after coating it with black gel coat, there is no problem.

 

That sketch of the tanks should help a great deal.

I used to build filtration systems and large exhibit tanks at places like the Monterey Bay Aquarium, Sea World, etc, we used ISO about 90% of the time. The reason for questioning ISO is because unless you know the exact product it may not be all that good, retail outlets that sell resin typically switch suppliers frequently due to price and you never know what it actually is. If that's not a concern then ISO will be fine.

 

Yes Ondarvr, there was a time ISO resins were questionable. But that was a long time ago. Maybe there are still some low grade going around but dealers are careful. I used to get Lloyds certified. It was a requirement. Now, just non-certified but I trust the dealer. It is about 40% more expensive than ortho.

 

I sell resins we make and have used most out there, there are still ones available that you wouldn't want to use on a hull or tank, they aren't bad resins, just not suitable for this purpose.

In the US the cost isn't a great deal more for ISO over Ortho, The jump to VE can be significant though.

 

rxcomposite, Wow, thank you for that file! That pretty much spells it out for me.

Ondarvr, any particular ISO and VE resins you would trust that are available in the US?

 

Most professional systems use concrete as the major support base under the fibreglass shell.

They either coat the concrete or rendered blocks with fibreglass, or lay concrete over the outside of a gelcoat/matt layer on the male mould.

The difference in price is dramatic, but you may need a forklift to move the tanks after they are made.

 

Concrete is the cheapest way to go but it is intended as permanent structure or large quantities of culturing. The ones we made are modular and collapsible so that it can be delivered to the site. Some just provide the concrete base and use empty (cleaned) oil drums or even the large square plastic milk container that Australia ships to us.

 

I used to have some hydroponic beds that were cheap and long lasting.

They were about 3 feet wide, or whatever works for reaching in from both sides, and however long I needed them.

You plan on filling the trays up with growing medium, but I found that to be a nuisance. The plants were anchored in one spot and couldn't be moved around so tall ones wouldn't shade short ones, harvesting left 'holes' in the plant cover, diseases spread rapidly, etc.

So I went to nurserys or garden centers and got hundreds of the 6" black plastic pots for a few cents each and filled them with the medium.

There are two ways to water the plants, either a piped irrigation or drip system with a timer or a handheld sprayer, and a flood system where a timed pump floods/fills the trays from the bottom, the pump shuts off and all the water drains back to the tank by gravity. Depending on the medium used and it's water retention, that's done maybe once a day or maybe once an hour.

Judging from the size of the tank and trays pictured, you couldn't flood all the trays at once or the fish would have no water.

Anyway, the trays I used were plywood bottomed with 1x4 treated wood sides, as I used pipe irrigation and the trays didn't hold any large amounts of water. If you want to flood the trays, use ply and treated 2 x boards however tall you need.

They have a roofing system that uses EPDM rubber, it comes in many widths, 10 to 20' and lengths of 100'. It's like inner tube rubber and most every roofer that uses it has leftover pieces they practically give away.

So you get 1 piece of the rubber big enough so it will cover the bottom, up the sides and ends and either the top edges of the 2x boards, or a little more so it comes down the outside of the trays.

You fold the rubber in the corners so there are no breaks and the thing is water tight, and screw some 1 x 2s around the top edge or the outside to secure the rubber in place. Any waterline/drain penetrations can be made with clamping type fixtures, like thru hulls, and caulking.

They are fast, cheap and long lasting. The rubber is good for 20 years or so, uv resistant and probably comes in white, but usually black.

Water weighs 60 lbs a cubic foot, so whatever you make has to support a lot.

 

Yes, thats why flooding is less popular now anyway. The popularity of drip irrigation from overhead, of for some crops, spray is increasing.

It allows better control of nutrient too, as you can link the drips to almost individual pots, if the plant is big enough.

When you have flooded beds, you have to ensure that the oxygen levels and ph is correct for a big amount of water - and then you have the algae problem that doesnt exist with drips.

I have just done a trial of chili plants, some with medium, some with potting mix, some with flood and some with drip. The results in cropping were too close to call, but the least work with the least monitoring was drips in potting mix.

 

The way that flooded beds worked as I understood it was the beds filled quickly and then immediately drained, so all the air/oxygen was pushed out by the water and then replaced as the water drained. Depending on the water retention of the medium, pebbles, soil, rockwool etc, the frequency of flooding varies from every 30 minutes to once a day or so.

My system was 6" pots filled with 50% potting soil, 25% vermiculite and 25% perlite, watered with a handheld sprayer to overflow every other day on a feeding schedule of Miracle Gro, water, water, Miracle Gro etc. Every two crops the medium was discarded, and new medium mixed, the Miracle Gro was only used once and then like the soil medium, 'discarded' to the lawn or flower beds.

I tried straight hydroponics, but after a week or two the ph always went berserk and the whole amount of water would have to be thrown out and remixed. The plants also suffered almost immediate harm when the ph balance went bad, whereas with the soil mix problems like that were buffered.