Aquaponic Gardening

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I presently am using a vertical hydroponic system in my greenhouse. I have a fairly large swimming pool that I plan to use as an aquaponics system.

I live in northern Louisiana, so I will probably wind up with catfish in the pool. In the interim, I am going to put in some rosy reds which are really a red color variation of fat-head minnows. they are supposed to be omnivorous so maybe they will eat up some of the  algae/leaves/crap that has accumulated in the pool. The catfish can eat them later...

I have been doing my reading, but still see alot of conflicting advice. I know I need to bypass the existing sand filter and that is not a problem.  I have a fairly large pump for the pool (20k gallons or so)..about  1 1/2 horse pump. I have no idea of the gallon/hr but I know it is big. It powers several jets into the pool with a VERY powerful flow.

What I was thinking of doing was cutting the existing lines and redirecting the flow into a large plastic barrel sitting on top of the diving board platform.

I thought of putting taps into the barrel at some point lower than the top  to feed the plant beds by gravity. i would have an overflow at the top of the barrel that would fall directly back into the pool. That way I would not have to worry about excess water flow.

I have planned planting beds on both sides of the pool along the deck. I think a simple ball valve will let me control water flow to each side of the pool for the beds. One side is far larger than the other.

Now for the questions...1. I have seen people talk about the necessity of a biological filter before the plant beds to allow for the nitrifying bacteria. Is that really needed, or do the planting beds themselves suffice?

2. As far as the plant growing beds go I am looking for the least expensive option.  For my present grow beds, I am using 4 inch sewer pipe with 1 inch holes spaced at 8 inch intervals staggered on 3 sides of the tube.  (Remember these are vertical). What are more economical options?

3. For the aquaponic system I was thinking about using similar pipe with connections that would direct the water flow into the first pipe and then in a zig-zag  pattern through the whole bed. then back to the pool. i think setting up mini bell siphons in each run (about 25 ft long) would be problematic....so...

4.Is an ebb and flow system that much more beneficial for plants than a continuous flow or NFT system?


5. i can always add fresh water to the pool and, by adding a tap to the barrel on the diving board, have a gravity fed source of water to run to my regular garden beds. i figure this will allow me to adjust for  for at least increased ammonia levels in the pool.


I welcome all comments and criticisms. I was trained years ago to think through a project to identify all the things that could go wrong and then correct them ahead of actually trying it.  However, this is all new to me.so I am doing this intuitively.

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Guess no comments/advice forthcoming.. I have located some food grade plastic barrels that I can use as filters.

LOL, I'll take a swing at it but by no means am I qualified for such a project.

With respect to bio filter before the grow beds: many systems are setup this way, the media growing bed is the filter, this is my style of system, and after the first media bed, the water will go into a DWC bed with a raft floating on top. I may have issue with too much particulate getting through to the raft bed if that happens i'll have to deal with it. My understanding is some peoplle take the approach of removing the solids prior to the water hitting the media bed or if they are only using rafts but that has the affect of removing a lot of what can eventually become a source of nutrients for the plants.

Your plans are really huge so would be very tough to manage, You would need a lot of fish to have much concentration of nutrients and then the volume of media bed to deal with that volume of water and nutrients would be huge. I suggest you do some searches on the site regarding swiimming pools - I know they are out there, I have read a few of them and recall some pretty strong warnings about the challenges you might hit.

sorry for the rambling but I hope that helps somewhat

Pat James said:

Guess no comments/advice forthcoming.. I have located some food grade plastic barrels that I can use as filters.

Well, I'm also completely unqualified to give a good answer.  However, you may want to look up the paper "How to Build a DIY Bio-Filter and Venturi for your Pond". 

Given that you are working from a swimming pool, you probably wont be able to build sufficiently large enough grow bed to filter solid wastes from the fish.  Instead, you'll need a pre-filter to remove solid wastes and then a bio-filter (such as the referenced skippy filter) to convert ammonia to nitrates.  You can then draw from the clean water source coming out of the bio-filter for growing plants in your green house.

One difficulty is that fish waste is lacking in calcium and magnesium that your plants will need.  For aquaponic systems, this is handled by adding these as a buffer to bring pH levels back up to 7.0 once the system is cycled.  It's not clear how this is handled with a swimming pool sized system.

Halemart was working on a pool system sometime back.  You might want to make contact with him.  I believe you'll need quite a bit of media filtering and rather light stocking - if you stock a pool heavily, then you'll need a gigantic amount of filtering.  Flood and drain is generally considered to be much more effective than ebb and flow.  

The food grade plastic barrels - consider standing them up on end and filling them completely with gravel.  Check for a source of Stalite.  If you buy by the ton, it's not expensive.  Otherwise, some other neutral PH gravel.  Check out 100 gal stock tanks for media beds/filters.  

Good luck 

Pat, is your pool plastic, plaster, or what? Above ground or in ground?

Bart, I disagree that a very large system would be tough to manage, or that you would need a very large number of fish to supply nutrients. My easiest systems are the largest, and the least stocked.

David, I disagree that Pat would need a solids filter, or a biofilter, independent of the grow-beds, though those are certainly options to be considered. I also disagree that calcium and magnesium are in short supply in fish waste. Most source water contains these minerals, and all fish food contains them in plenty, as they both are required for fish health and growth. I have certainly never needed to add them in almost 4 years of growing AP. Use of rainwater or very soft water may change that result, however, so you should always test your levels to be sure. If deficiencies of either of those minerals are showing in your plants, it may be from nutrient lock-out due to high pH, not the lack of the minerals. And I personally favor the plants when I choose a target pH, because the fish don't seem to mind, and the plants do. I keep mine between 6.0 and 6.4

Questions? Here's my $.02...1. I have seen people talk about the necessity of a biological filter before the plant beds to allow for the nitrifying bacteria. Is that really needed, or do the planting beds themselves suffice?

Yes, the grow-beds themselves provide plenty of surface for nitrifying bacteria, especially if using media. Even without media, DWC beds need no extra space for nitrification. I recently heard that up to 40% of the nitrifying bacteria are in the water column itself, not the just the hard surfaces. I have 3000 carp (only 2" right now) in a 1000 gallon tank tied to 160 sq ft of rafts, with no media at all, no pumped air, no solids removal, no degas tank, and only a 50 gallon barrel full of bird netting between FT and DWC.

2. As far as the plant growing beds go I am looking for the least expensive option. For my present grow beds, I am using 4 inch sewer pipe with 1 inch holes spaced at 8 inch intervals staggered on 3 sides of the tube. (Remember these are vertical). What are more economical options?

Odd. Both the use of vertical growing and 4" pipes are inherently expensive and problematic. By far the cheapest, fastest to build, and least maintenance way to build is using DuraSkrim 20 mil liner ($180 for 100' x 6') stapled to a wooden 2x4 frame and 2x2 stakes, on grade, with Beaver Plastics floating lettuce rafts, or plywood "rafts" that rest on a ledger near the water, but not in it. Pumping water up several feet to supply vertical pipes is not worth the electricity in my opinion, and metering the water through dozens (or hundreds?) of small orifice drip lines or holes is so ridiculously labor intensive. You are used to vertical Hydro, and that is different. Clearing a little salt block now and then is no big deal, but bio slime from aquaponics is WAY different. That's my opinion, based on experience.

3. For the aquaponic system I was thinking about using similar pipe with connections that would direct the water flow into the first pipe and then in a zig-zag pattern through the whole bed. then back to the pool. i think setting up mini bell siphons in each run (about 25 ft long) would be problematic....so...

Ah, I may have gotten ahead of myself with the last comment. So you are growing vertically with horizontal pipes, not vertical pipes. This simplifies the water metering, but I can't fathom how you can drill holes on three sides of a horizontal pipe and expect to have it hold water. What am I missing? Do you have two different vertical systems, one with vertical pipes and one with horizontal pipes? I'll assume you do. The slope required on a 25' run will surprise you, and the daily change in hydraulic dynamics will to. Restriction from rapidly growing roots and the solids collected in roots are hard to predict, and a blockage could have you draining your swimming pool while you're on vacation. I have seen roots nearly block flow in a vertical 4" pipe. If you go through with the long run horizontal plan, stick to quick crops like lettuce so you can remove the whole plant before roots block the flow, and forget all about strawberries and tomatoes.

4.Is an ebb and flow system that much more beneficial for plants than a continuous flow or NFT system?

In pipes? Keep it simple. NFT will heat up like tea-water in the summer, so I'd recommend a high volume flow thru a pretty steep slope, maybe 3-4' of drop in 25' of run. This sort of slope of course eliminates the possibility of ebb and flow in a 4" pipe (and George, E&F is the same damned thing as flood and drain, with perhaps an arguable inclusion of pump location in the technical definition of the two)

5. i can always add fresh water to the pool and, by adding a tap to the barrel on the diving board, have a gravity fed source of water to run to my regular garden beds. i figure this will allow me to adjust for for at least increased ammonia levels in the pool.

I don't follow this last one. But whatever. I think your project is doable, and when done right will be very easy to maintain and be pretty dang productive. I have planned a living swimming pool since last winter, and I am just now converting an 18' diameter above ground pool to test the principles before I commit to tractor and plaster. I have the pool overflowing thru an SLO into a swirl filter, into a kiddie pool of water cress, scuds and cherry shrimp, into a second pool of barley straw, then pumped back to main pool. There will only be 30-40 lbs of fish in there, and I intend to swim in it. Let's swap pictures of our projects, eh?

Jon, I agree that a bigger system is definitely easier to manage, I thought there was a limit to this rule though, so when I saw 20000 gallons, I thought that would have been over the "big is beautiful" range and into the "holy crap now what" range.

My experince with my 300 gallon system is that the plants struggled until we reached a point where the nutrients in the water came up a little - had 40 2" goldfish for two months. I expect based on what you are suggesting that I simply had too many plants for the amount of fish waste.

Based on what you are saying, I have tripled the size of my next system.

cheers

 

Hehe, Bart, I think bigger systems have unique challenges of their own, but are generally easier concerning stability. One concern I remember reading about in the forum was a much longer period of time to cycle, meaning a user filled with water, added fish, started up pumping and feeding, and simply didn't see an ammonia spike for a couple of months. He assumed it cycled without spiking, but the spike did eventually come, and what can you do about it when a 50,000 gallons reeks of ammonia? Bart, I'm a big advocate of low pH in aquaponics, and my guess is that if your 300 gallon system struggled for a bit, it may have simply taken a while for the nitrification to bring the pH down into plant usable range. Just a thought. Good luck with your projects :)

My pH is about 8.2...I'm in the nitrite spike phase and my plants are doing GREAT ! (No sarcasm and no deficiencies what so ever)...Just thought I'd gloat a bit ...Of coarse I have plenty of plant essential elements in solution already thanks to cycling with humonia, so the pH matters a good deal less it seems.  Can't wait to see how they react when the pH drops   (or when I decide to lower it)...I'm with you on running an AP system on the low pH side (once it's been cycled and running a bit)...

Jon, are you serious?!? Who the HELL would put a 50,000 gallon system together and yet be so clueless of the most very basic of basics? Way to chalk one up for the side of 'commercial aquaponics' sheesh...

Although I am still a fan of diving into the deep end with something (pun intended) Id agree with Vlad that starting with something smaller to get your feet wet with aquaponics/pond culture might be a smarter move. You reduce your risk of making mistakes hurt your wallet, and your passion for your new found hobby. I think starting with the pool you may find yourself drowning over your head.

Also before investing in converting a 50k gallon system, try sketching out your design. Then put it away and forget about it for a few weeks. Play with the small system some more. I bet before you get to the pool, if ever, you will have scrapped and redesigned it half a dozen times in the process and probably all for great reasons.

Amen to that, Chris, but bigger is not necessarily more expensive. He already owns the pool, and adding fish and some grow beds can be a weekend project. In my present case, I took over the kid's swimming pool at the end of summer. We quit putting chlorine in it, allowed the leaves to blow in, and once it turned green and swam with mosquitoes, we added some catfish, bluegill and carp. The filtration tanks are $7 dollar kids wading pools on end of summer close out, a couple $4 bulkheads, 2" pipe, a $20 dollar pump, and we've got a big aquaponics system for possibly a living swimming pool for less than $50. If if all fails miserably, we water the fruit trees and roll it all up until next summer. It costs me about the same for one little barrel-ponics system, and I just can't enjoy a swim in half a barrel, dammit.

Vlad, I'll look for the thread on the big system I mentioned, but it was certainly not commercial, nor much invested. It was an earthen pond, that was lined, filled, stocked, and plumbed to some raised bed style media beds. If it was a mud floor, I'm sure the ammonia would never have spiked, or in Pat's case and mine, if it is a neglected pool with leaves, algae, and insects, then cycling can be skipped as long as stocking/feeding is light

All far points for sure. I guess I more meant that the likelyhood of  mistakes costing a lot more $ or the discouragement when making noobie mistakes turning everything teats up would be bigger in a large system. Not something you are worried about at this point with your experience. 

I guess I am just thinking from my perspective of being quite methodical about approaching things. 

Although it is just one way to go about it, I would first understand how things work, for example knowing some of the basics like what is a bio filter and why do i need it and where does it go as indicated in question 1. Second would be to build a prototype. Does it work? Why does it work? Why did it fail? Once that works, jump into the "real" project, the pool.

I would love Pat to succeed with converting his pool. I think that would be awesome, but avoiding failure is always nice especially if it would be discouraging.  If Pat feels that messing things up, pumping out the pool and waiting until next year is an option then sure go for it! If best chance at succeeding would be preferred  then some research and a prototype might be wiser.

What I do know from reading this forum almost everyday for a year now is that until I actually build and maintain a thriving system, I really know nothing at all 

I just got off work and read through the comments. So I'll start explaining a little more clearly. I have a in-ground plaster pool that was opened last summer. You 'open' a pool by socking the pool with a big load of cholinre to basically kill off everything in it. Then you turn the filter back on and start brushing the pool and backflushing the sand filter.  In- ground pools are not drained, at least not in a place where you have a water table that can either pop that pool right up out of the ground and crack it. Maintenance on a pool is a daily or every other day affair and becomes a pain quickly. My wife and stepson wanted me to open the pool but I told them ONLY if they would participate in the daily work. They did not so the pool stayed green.

Early summer, I had tadpoles growing and insects in the pea green water. How I managed to not have a major mosquito problem, I have no idea.  I turned 50 shiner minnows loose the other day to eat whatever they want.

Chris, I do understand the principle of a biofilter, especially in a smaller tank where your bio-load is fairly heavy. I owned a pet store for 10 years. My comment there was how much I could rely on the grow beds to act as that bio filter.


The pool is a little over 30' long and about 18 wide. almost 4 ' deep in the shallow end going to about 5' in the middle. Then it falls off quickly to about 11 ft. It is designed as a diving pool. I have a 1 1/2 horse pump inline. I would cut out the sand filter and direct the water back towards the pool. Now at ground level that pump puts out alot of pressure.Water flow is not variable, so I figured to run it up into an elevated barrel that would act as a cistern.  Taps placed into the barrel  would utilize the weight of the water to force it out into the grow beds. Think in terms of a water tower where you pump water into it continuously and drain as needed.

Now my guess is that the pump will fill that barrel faster than gravity can send it to the growbeds out 2 or 3 taps. For that reason, I figured an overflow at the top of that barrel to run either back to the pool or to a second barrel placed lower down filled with some kind of media before it drains into the pool.

I've though about direction of flow into that first barrel as well.I would direct it to the side so it vortexes around the the sides. That way heavier solids would tend to drop to the bottom,... , again depending on how fast the water was flowing.

Jon, I confused you about the tap I planned to put onto the bottom of the barrel. It is to periodically drain off those materials and water my ground garden beds at the same time.

This system would probably maintain a light population of minnows as the returning flow would help aeration and the pool algae would take care of a small amount of waste. But the purpose is to ramp things up.


Jon, The hydroonic system in my greenhouse is a separate entity.. It is 4 inch sewer pipe hanging from a rack. Each tube averages 40 inches long ( I utilized the full 50 ft of pipe I bought). I bought some house gutter material for return to my reservoir, an 18 gallon tote. I have a 500 gph fountain pump that I got for $50 at a big box store. My water lines are flexible polycarbonate that I scrounged from the hospital operating room. I run a 1/2 in line out of the pump up about 5 ft and then step down to  a 1/4 diameter loop . Off this loop I have 1/4 lines to each tube. This greenhouse is too far from the pool to incorporate the systems.

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