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fritz_monroe
03-23-2011, 01:53 PM
Hello folks, I'm posting here mainly as a place to get put together some ideas for my first aquaponics system. I'll also use it to document my building process when I get to the actual build.

I'd appreciate any corrections to my thinking and my plans.

First the idea came from an interview that I heard with the lady from Colorado Aquaponics. She talked about a small AP system that she uses to feed salads to her family of 5 all through the Winter. That got me thinking that this is something that I'd like to do.

Here's my wants. I need it to be fairly small. I think the kids would like to watch the fish, so I'm thinking that an aquarium is what I'd like to use as the fish tank. I have a 20 gallon aquarium that I'd use and I saw on here someone cutting through the glass to put in the drain for the fish tank. I want to be able to grow a bunch of salad greens, enough to feed my family of 4.

What I've been finding online seems to point to a system that has the fish tank, the grow beds and a sump. Until I saw the thread where they cut into the glass, I didn't think I'd be able to do this type of system.

Since the fish tank is 20 gallons, the grow bed should also be at least 20 gallons. For the grow bed, I plan on either creating the beds out of wood and pond liner or using something like rubbermaid containers. They will be about 9-12" deep.

For the water, I'll have the 18-20 gallons in the fish tank. The grow bed will have the media taking up about half the volume, so the bed will have 9-10 gallons when filled. this means the sump needs to hold at least 10 gallons. I was thinking of a 5 gallon bucket, but obviously that won't work, but a 18 gallon Rubbermaid tote would work.

I'm not really sure what type of media to use. I think that using Hydroton may be the way to go. This is a small system, so the cost would not be too much. I also think that it would reduce the likelihood of having the media negatively affect my learning curve.

to be continued.

fritz_monroe
03-23-2011, 02:29 PM
A couple ideas about the actual building of the system.

The fish tank would be at the highest level. I'd drill a hole in the side, near the top. The drain would go from the bottom of the tank up to the hole and out to the grow bed. So not to drain the fish tank, the top of the drain would be open to the air.

The grow bed would have a bell siphon type of thing going to drain it. My understanding is that the water should come up to about an inch below the top of the grow media. The siphon would have holes about an inch above the bottom of the grow bed to break the siphon and not completely drain the grow beds.

This water would drain into the sump. There would be a continuously running pump in the sump going back up to the fish tank.

The pump, I've read that it needs to turn over all the water in the tank 4 times in an hour. Is that correct? I also know that I need to put oxygen into the system. If I set the pump up to splash the water back into the fish tank, will that put enough oxygen into the water? I know I could put an air pump and air stone into it, but if it isn't needed, why add the complexity?

keith_r
03-23-2011, 05:57 PM
it sounds workable, but i'd say put the gb above the ft, with the sump below the ft
pump from the sump into the gb,, which drains into the ft, bringing oxygenated water directly into the ft, which overflows into the sump
or go sumpless and pump from the ft to the gb
adding a small aerator isn't really going to add to complexity and will be good for the fish

you'll probably have some solids settling in the sump that should be fairly easy to siphon out as needed
and i'm sure others will chime in with ideas

fritz_monroe
03-23-2011, 06:32 PM
Thanks for the feedback.

I didn't want to go without the sump because of the amount of water that would be pumped out of the FT. With the sump, the FT wouldn't get so low.

Why would the water coming out of the GB be more oxygenated.

keith_r
03-24-2011, 07:05 AM
as the water drains through the gravel more surface area is exposed to the air..
if it drains into the sump and, it will start to "off gas", if it drains into the ft, you're adding oxygenated water directly to the ft where you want it

fritz_monroe
03-24-2011, 10:17 AM
That makes sense.

This brings up a couple more questions.

First, is there a test kit that will test for ammonia, nitrates and nitrites? I'd hate to put a bunch of work into it only to not have the proper biological actions happening in there.

Second, in the sump, would I be able to put a raft with some plants in it? Do all plants require oxygen to the roots? If so, how do you provide that to plants in a raft?

Thanks again

keith_r
03-24-2011, 11:20 AM
i use an api master test kit (fresh water) found at the pet store for about 25 bucks,
tests ph (high and low range), nitrate, nitrite and amonia

Oliver
03-24-2011, 03:35 PM
Fritz,

Welcome to the world of Aquaponics.

Your design is workable. Personally, I like the simpler grow bed higher than the fish tank approach. This eliminates the need for a sump tank. You are correct in not draining all of the water from the grow bed. If the grow bed has the same container volume as the fish tank, you will only be exchanging one third of the fish tank water with each cycle. This is due to the fact that you won't be filling the grow bed to the top (one inch below the top of the media) and, as you said, you will not be draining all of the water before break of syphon.

I have found that cutting the syphon shroud slots a little high helps from draining so much water from the grow bed with each cycle. By adjusting your cycle to about four times an hour, you will be adding dissolved oxygen back into your fish tank, as well.

With this design, your fish tank's water level will only vary by about one third its rated capacity. This should be just fine for the fish. In addition, the flow back of the water from your grow bed will help aerate your fish tank water. You will need to add an aerator and air pump to your fish tank. As for air pump, I recommend 7.5 gallons per hour of air for each gallon of fish tank. Some would say that is a lot of air but from my measurements of dissolved oxygen it is what is required. Also, jetting back some excess pump water into the fish tank helps aerate its water. This requires you to rate your water pump GPH at about 120% of the grow bed hourly exchange at six feet of head. You will want to be able to adjust the flow into your grow beds in order to set your syphon timing. This adjustment should be separate from the jet back into your fish tank.

It is also good policy to have the air pump on battery backup in case you have a power failure. The size of the back-up will depend on how long you want to insure for your power failure. We recently had a 20 hour failure, that was the longest we've ever experienced; but fortunately we had installed a back-up system for our house which included a generator.

I agree with keith_r about the API Master Fresh Water Test Kit. It is what we use, as do many Aquaponics enthusiasts.

With regard to using a glass aquarium, if your fish tank is down low you will be able to view the fish from above just fine. A plastic fish tank, as well as grow beds, are much easier to work with (drill holes if needed etc.) than is glass. They are also less expensive and lighter.

A 20 gallon grow bed is only going to give you about three square feet of growing area, less if it is one foot deep and room for the syphon.

What kind of fish are you planing on raising?

Oliver

fritz_monroe
03-24-2011, 04:57 PM
Thanks for the responses.

I'm thinking that I'm just going to put goldfish in the first system. This system is to convince my wife to do the big system with food fish in it.

As for the tank, I have a 20 gallon glass aquarium that I picked up off Freecycle. One of the reason I want to use this is I would like to keep this as inexpensive as possible. That will also help me convince the wife.