Aquaponics---What's your take?

[RichnSteph]

Oh, I think that is a pretty good price. Yes, plant in the river rock. The lava is just brutal on the hands and it makes you not want to mess around in there, which you need to do. The greater surface area and low weight of the lava make it worth having as the bottom layer though. Is the wind such a problem there that you really need the break that the high sides would provide? A bit more gravel depth would be helpful. Yeah, the hydroton is prohibitively expensive. I only use it in net pots in hanging NFT tubes, where weight is an issue. I wonder if you can get expanded shale at a good price where you live? I really like that stuff too, it's less expensive than hydroton, but hard to come by out here in AZ. It's regular shale that has been super heated to a point where it puffs up. It's smooth and is super light weight. I seem to recall that they make it in TX.

I'd not considered expanded shale. Thank you for the heads up! There are a few places here and there that sell it anywhere from $135 per yard to $63 per yard depending on the size and if it's been sifted. I'll start researching that more in depth now so that I can make an informed purchase when the time comes to get some media in the beds.

RichnSteph.

 

[RichnSteph]

I think I may have shot myself in the foot here. We're going to use one of the big grey troughs we bought last weekend for the fish tank and the other for our first grow bed. We'd like to start with just the one grow bed and one tank and work our way up as we get more skilled at this. The problem is that the water tank is going to be just a tad over 750 gallons once full (this is three times the volume I was initially planning on) and I've read that you want to cycle the entire volume of water through your grow bed once every hour. This presents a problem. I've already got the pump for this and it's rated at 6 gallons a minute (it was free) so even if I ran it all the time it'd only move a little over half the water per hour (360 gallons). Our plan is (was??) a flood and drain system where the pump would run long enough to fill the media with water up to the top of the roots and then turn off for to let the system drain out. I'd prefer not to run the pump more than once an hour so that it lasts longer and doesn't eat us up in electricity. Everything I've read so far says that a Flood and Drain method is the best way to go followed by the Constant Flood method.

Thoughts or advice? Perhaps a better method that I've not seen yet?

RichnSteph

 

[Gallo del Cielo]

I think you could make it work, even though the flow-through rate will be less than desired, you can offset that a bit by stocking fish at a lower density. I think you'll quickly want to add another grow bed once you see what you can do with it, which will help. The main challenge will be making it work without a sump tank. Will the difference in the volume of water between flood and drain impose too much variability in the water level in the fish tank? You'll need to calculate how much water the grow bed will hold at the high water mark. Decide the level of gravel you'll have in the grow bed, subtract an inch since you'll probably only fill it to within an inch below the surface, calculate that volume and then multiply by .35. The actual value will vary between 30% and 40% water depending on what medium you use, but that should give you a ball park figure. You can then decide if the volume of the fish tank will vary too much between high and low water. I'm guessing that the volume of water your grow bed will hold will be something much less than the 360 gph that the pump will produce so you shouldn't have any problems filling the grow bed once every hour, but you'll have to figure out how long it needs to be on in order to fill the bed. One final issue that immediately comes to mind is the issue of the timer for the pump. I've not found an inexpensive solution for a timer that comes on for a period of time every hour over a 24 hour period, however, I also haven't looked recently. If you find one, let me know.

 

[RichnSteph]

Thanks Gallo.

I measured the actual tank dimensions and it'll hold 785 gallons filled to within a inch of the top. With a filled area of 7'x6'x10" in the grow bed I get 262 gallons, knock the 10" down to 9" for actual fill and it's 235ish. Multiply in the .35 and I get 82 gallons. My pump will run 90 gallons in 15 minutes with optimum run, I don't think the extra couple of gallons over that area will matter overly much.

I did find this timer.
http://www.theaquaponicstore.com/Grounded-Timer-15-Min-Cycle-15-Amp-24-Hour-p/apphf005.htm

As far as a second grow bed goes I've got a second identical pump to the first sitting on a shelf and if I can make one work with that timer then a second timer/pump set up for the next bed should be easy. I'll just make sure they cycle about a 15 minutes apart so that the one bed will be partly drained before the second one starts it's fill cycle. I don't think pulling 90 gallons of water out of the fish tank (which is just about 3.5 inches over the total area) will hurt the fish overly much. We do plan to stock lightly at first since we'll be harvesting perch out of the river at my grandmothers house and I don't know how many we'll actually catch.

Thank you again for all the advice and help. Once it's all put together I'll send you some pictures so you can critique it for us.

RichnSteph

 

[Gallo del Cielo]

That all sounds very do-able. I agree, the extra gph in 15 min. won't matter much, nor will the 90 gal. displacement in the fish tank.

Another thought: you may need aeration in the tank to assist in oxygenation when the grow bed is filling and no water is flowing into the tank. This will likely be more of a problem during the warmer months when the water will hold less oxygen. Oh, also, consider installing an "Affnan" style bell siphon if you haven't already. When I was running a siphon, it seemed to be much more reliable than a standard bell type. Finally, consider using a Uniseal when putting pvc through the growbed wall (as long as it is less than1/2" thick). They're super easy to install and never ever leak. I'm looking forward to seeing the finished project!

Thanks for the link to the timer, I've bookmarked it. There wasn't one available when I was first starting out and that looks great for the price!

 

[RichnSteph]

The grow beds already have drains installed from the factory, one less place for me to cause a leak, so I'll be using those to get the water back to the fish tank. I'm going over the top with the fill lines so no holes there either. I'll take a look at the siphon but to be honest I was thinking a stand pipe with small drain holes near the bottom since I think it'll be easier for me to engineer and build.

I'll keep you updated!

RichnSteph

 

[trsturself]

We are hoping to get an AP system up and running in 2016. We live in CO so will need a greenhouse to keep everything above freezing over the winter. We won't have the money for the greenhouse this spring, so this is being put on the back burner. I'll also have a large regular garden but would love the fresh fish and a few veggies over a longer season.

I plan to start with tilapia and then move to bluegill once I get all the kinks worked out. I prefer them to tilapia and they can handle the cold better. Tilapia have to have 70deg+ water but bluegill are good at 60-80.

We have a great AP place here (www.thegrowhaus.com/). We did a tour there with our homeschool group. It was really interesting and I learned a lot. They also mentioned using a smoother material to plant in for the sake of your hands. My daughter loved it and we got her the materials to build a small AP system over her 10g fish tank in her room. She'll only grow succulents but it will be a great test system. It will have lava rocks since she won't be planting over and over again and a bell siphon. I think I'm looking forward to it as much as she will be. lol