some basic questions

[Pat James]

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.

[Pat James]

As far as post-barrel plumbing was concerned, I was planning on a couple 2 inch taps about 1/2 way up the barrel on one side and a single tap on the other. Each tap would go to a manifold fitted with ball valves and stepped the pipe down to 1' or even 3/4 pipe to fill the beds. Caps on the pipe ends would be drilled and fitted with elbows so the water level could be maintained. I was looking to avoid threaded pipe and a bottom drain in a round tube would be harder with out leaks.

There were several things that I did not think of when considering grow beds. The main one was the size of a root ball blocking water flow. And if I want a garden, I need to have a variety of produce growing, not just lettuce.

The systems I saw online were growing herbs or lettuce and  for the most part, were newly set-up. One guy used a series of 3 inch diameter pipe  mounted on a rack. His system was much taller  than I was considering, but I liked the idea of his grow area with a  small footprint. I think he had 160+ plants on a 10 X 6 footprint.

My usable area on each side of the pool is about 12 ft wide by 30 ft long on one side and 7 X 30 on the other. That leaves the ends of the pool open.

[Bart]

Interesting thread Pat, could you maybe float rafts right on top of the pool? I know you would need to net them into an area so the fish can't get at the roots, but that seems doable with some netting and a PVC pipe frame. You could suspend the net say 12 inches below the rafts. It would save some hastle making up grow beds and really utilize the space as well as cut down on the alge. You would still need some media somewhere in the system to provide filtration and surface area for the bacteria to live but you could cover that off with a few of the barrels you are talking about filled with gravel.

I hope you share pictures whatever it is you build.

[Bart]

Jon, there's a solid chance you are onto something there. My basement system was new in September and I used reclaimed clay brick for the media. Not sure yet but this may have been a mistake, PH has sat at 8 since the beginning, this is the level of my topup water as well though so doesn't seem too big an issue. 

I just bought the miratic acid last weekend to start sloooooooowwwwwwllllllllyyyy working it down thru my top up water. Any suggestions on how much to put in say a 5 gallon bucket? And what PH should I try to achieve in the top up water? I'm in no hurry, rather be safe then sorry and end up with floaters.

Vlad, I'm gonna have to go back and re read that post and about a 100 others I have read from you on nutrient issues to see if I can figure out the other angles to my issues - ah issues, I have so many .............. where to start.

Pat, sorry to get off topic.  Cheers I meant cheers  but cheer is good to

Jon Parr said:

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

[George]

Well Damn, Jon, I say that location of pump does not determine the difference between the two but location of the input of flow has everything to do with it.  If your flow input is at the bottom of the media, then solids can flow in and ebb out.  If the input is at the top of the media, then solids are more likely to be captured (filtered).  So, I suppose whether Ebb and Flow is more effective than Flood and Drain depends upon your definition of the two.  The concept of ebb and flow is from the rise and fall of tides, which is much different than our use of flood and drain in aquaponics. 

Pat, all the best in your planning.    I think it's great that you have a pool to work with.  It has a lot of potential.

Jon Parr said:

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)

[Vlad Jovanovic]

IMO ebb and flow is probably waaaay better suited to mineral hydro than AP, or any kind of organic input hydro/bio-ponics...and I'd probably stay clear of any piping below 1" whether flood and drain or ebb and flow (the smallest I used in the new 'big' system is 1-1/4")...because of bio-slime build-up that seems to happen after a time...could clog up the AP arteries quicker than curly cheese fries... 

I'm using the terms "ebb and flow" and "flood and drain" as they are defined here on this forum in the "Glossary and Terms sections (most hydro literature defines them the way they're defined here).

Bart, yeah, dealing with 'issues' is much easier before fish are put into the system, but I'd be happy to try and help out if I can. Brick pH huh? Probably depends and the sediment they were fired from. Try putting some in a jar of some kind of acid, like vinegar or diluted HCL...see if the bricks fizz a bunch or not. And/or put some in a jar of distilled water and leave 'em there for 5 six days...then test the pH of the water...I'm betting (and hoping) it's just your source water though. It can take a while for the bacteria to use up the carbonate alkalinity...Sorry for being off topic Pat.

[Pat James]

Hey people have apologized for getting off topic. To me , that is the natural progression of any discussion.

Today I started netting out the detritous from the bottom of the pool. Most of it will be put into existing compost beds.

[Pat James]

After doing alot more reading I have revised my plans. I think b the time I  implement the system, it will be far from what I originally thought of.

[Jon Parr]

You are correct, George, thanks for the comment. I've been using the two terms interchangeably in my mind for so long, yet flood and drain in practice, that I lost track of the input location difference. Thanks

Bart, I bet it's possible to calculate the ammount of acid needed to drop your pH, but the testing and math exceeds my desire to know. I can say, that I recently started a new system and it took 2 gallons of 15% HCl to drop pH, I think from 8.6 to 6.8, slowly aded over 2 weeks. I put a pin hole in a Dixie cup, and add some acid to the cup. It drips in over several hours, and I recheck pH the next day. If you have base leaching components in your system, it may take several weeks to bring it to target, and some maintenance to keep it there. When checking pH after acid dosing, the immediate reading is only useful in determining how the pH was immediately affected, as the actual pH will likely rebound the next day after waking up the carbonates. Use daily readings from the same time of day to determine target pH, and remember that daily pH fluctuations occur, with the lowest readings in the morning.

[Pat James]

Couple of things. I went to the big box stores to price lumber. and pond liners.  The weight of a 1 ft deep growbed, whether 3X6 or 4X8 is going to great.  What thickness plywood do you use for the bed? I found the plywood to be the most expensive component. 2X4's are relatively cheap.

I have also thought about using plastic barrels cut in 1/2 lengthwise. In this case each bed would be smaller  (less than 2X3' according to some online) and the complication will come with the extra plumbing of each bed. Supports constructed of mainly 2X4 with heavier lumber for legs would be cheaper. But I need to calculate which would be more economical to build.

Jon, I did a google search for the duraskin liner but could not find the liner you mentioned.. I got gloes and a bunch of other products. Do you have a link?

I went to the local "pond and garden" store today but their prices for supplies were totally out of sight.

[Vlad Jovanovic]

DuraSkrim... http://www.globalplasticsheeting.com/Portals/32796/docs/durasrkim%2...

It's been over a year and a half since I placed my order, but I believe I talked to a guy named Ed (760)-597-9298

[Vlad Jovanovic]

The stuff is incredibly strong...TCLynx has built some new grow beds with the stuff without using any wood (since she lives in termite country) here's a pic (not the foreground, but the grow beds in the back... the metal rails are probably more expensive than plywood, but you could probably forgo the plywood and use 2x4's (hammer tack/staple the liner to the 2x4's)...again it's pretty strong  stuff. Ridiculous tensile strength, trapezoidal tear strength etc...for something that thin...

[Jon Parr]

Yep, Vlad, and I got mine through the same source. Cost varies for volume, I'm sure, and so does shipping, but I got 10, 100' rolls for less than $2k delivered.

And wow, congrats to TC on those rail beds. I helped build those when I was there a couple of months ago. They look great.

I let the earth support the troughs, and stakes and 2x4 rails to support the sides, no plywood. For media beds, I use free blue barrels gun-nailed into 2x4 rim frame on posts, again no plywood, cheap cheap.