Sunday, November 28, 2010

Minor Surgery, Swirl Filter and PH Woes, Nifty Screens

My swirl filter turned out to be a partial success. That also means it was a partial failure. The problem was with the drain pipes from the tank to the swirl filter. These pipes were a "left-over" arrangement from when I had my system set up with the grow beds emptying into the fish tank. The water returned through these 1" pipes into the tank.

With the CHOP system, these pipes were to act as overflow drains so that the tank water could fall into the swirl filter and then into the sump. The problem is that I had too many 1" pipes too close together, and there was not enough concrete between some of them, resulting in some serious leakage. When they acted as drains from the grow beds, there wasn't a problem since the water in the tank was never close enough to the pipes for there to be water leaking between them.

The only way I could think of to fix this problem was by removing the pipes completely by knocking the tank wall down to the pipe level, replacing them with one 3" pipe, and re-pouring the concrete tank wall. Then I'd need to wait at least a week for the concrete to cure enough before applying tank sealant, which itself will require another 3 days to fully seal.

Of course, this would mean draining the tank and coming up with a makeshift tank and aquaponics arrangement in the meantime. I removed the blue barrels that were acting as sumps and replaced them with my third cattle water reservoir container. This is now in place and receives the grow bed water. So, we're back to the original type of arrangement while I wait for the concrete to cure.

Current Tank - Grow Beds Drain Into Tank. Former Concrete Tank Undergoing "Surgery"

New 3" Overflow Pipe and Repaired Tank Wall

Swirl Filter

The swirl filter worked pretty well. I used a discarded washing machine drum and fitted a pipe down the middle. The pipes from the tank (the 1"-ers) I connected to large 3-inch pipes that went vertically downwards into the tank. These I drilled plenty of holes into the bottom so that all the tank water falling into the swirl filter would be coming from the bottom of the tank, where most of the particles are. The over flow pipes were connected to elbows and extended so that when they drained into the swirl filter, they entered the filter all the way at the bottom. This would force the water in the tank to travel from the bottom all the way to the top, and allowing for the maximum distance possible for particles to drop out of the water before the water drains through the stand pipe.

Washing Machine Drum Acted as Swirl Filter. Sorry I didn't Get a Picture of it When Fully Set Up

Although it only ran for a day and a half before I had to shut everything down due to the leakage problems, it collected quite a layer of particles in the bottom. Unfortunately, these washing machine drums are not made with the same fittings as PVC so in addition to my tank leakage problems, there were also leaks in the swirl filter.

In my next version, I'll just use a portion of a blue barrel. The principle works quite well, which is all that matters. The washing machine drum will have to find another use.

PH Woes

In the meantime, PH levels continue to be high (8.2-8.4). This is after changing the gravel with gravel I had already tested to ensure it would not raise the PH. I can also rule out the concrete in the tank since for the last week no water has been in contact with any concrete. I've gone from trying to lower it with lemon juice to using phosphoric acid. Every time I lower it (to say 6.8-7.2), it just climbs right back up to the 8.2-8.4 range in a day or so. I've also changed a good portion of my tank water (on several occasions when my nitrates were too high) with water from the spring which has a PH of 6.4-6.6.

I have to say I am completely befuddled. For now, I will continue to lower it by adding a little phosphoric acid every day. If there is something in the water that is buffering the PH, it will eventually be neutralized by the phosphoric acid and then I can keep it at a lower PH. That is the hope, anyway.

Removable Greenhouse Shades

Since I've had extra time while waiting for the tank to cure and so forth, I decided to install some greenhouse shades.

My greenhouse consists of a double-pitched roof, with one side pitched about 3 feet higher than the other so that there is a natural exhaust vent for hot air to escape through. The roof is transparent polycarbonate roofing sheets and the sides are wrapped in anti-aphid screening.

When I first installed the roof, I thought it would be a good idea to also seal the roof on the inside with anti-aphid screening, since there are gaps and cracks in any roof that may allow bugs in (even though it may be water-tight perfect).

It turns out that is not such a good idea. The screening material is white, and when installed horizontally, it makes the inside of the greenhouse painfully bright - to the point you do not want to be in there.

I decided to remove this material, and also looked into installing some shade material over the plants. After researching typical greenhouse shade material by talking with a local provider, they told me the most I want to shade is by 50%. Shading material comes in different "densities" allowing you to block anywhere from 50% up to 99% of sunlight, and what you use depends on what you're trying to grow. Leafy vegetables, tomatoes, and just about everything else I have need lots of sunlight, so there is almost no reason to shade at all. However, I wanted to be able to put something up, if only for when working inside the greenhouse.

I devised a removable shade clamped on PVC pipe and hung on wires. So far, it works pretty well. I can make the shade open or shut by pulling on one of two sets of ropes. It works just like a horizontal curtain. It took a while to figure out all the "bugs", but now that I have one quadrant of the greenhouse done, it won't be too difficult to do the others.

I also decided my fish needed some shade. They are supposed to prefer dark spaces, plus all the sunshine promotes algae growth. This makeshift shade will do for now:

Moving the fish to the temporary tank I assume was pretty stressful on them. Unfortunately, one of the bigger fish died. So far, it looks to be a one-off incident as none of the others have died and that was three days ago. The good news is the fingerlings are doing quite well. I know you are supposed to separate them from the grown fish, but so far they do not appear to be being eaten. Here you can see three different sizes of fish:


  1. In your swirl filter redesign with the barrel, you might want to make the standpipe overflow the same diameter (3") as your fish tank overflow that is feeding the swirl filter. At a certain flow rate, your swirl filter might overflow with the smaller 1" exit.

    Re: pH, maybe try adding Sphagum Moss to the gravel. It is typically used as a growing medium for acid-loving plants, and it absorbs water, so if your system ever shut down, your plants would have a temporary source of water.

    I love the shade cloth system. If overheating ever becomes an issue, you might want to put it on the roof to block solar radiation from entering the structure. There is a shiny aluminum shade cloth that offers excellent heat protection, while also providing sufficient light for plant growth.


  2. I did some experiments with softwood charcoal in a jar of water to observe pH changes. The charcoal consistently lowered pH in spite of a source of calcium carbonate also being present.

  3. Just read this piece:

    It doesn't recommend using peat moss because it will break down over time and pollute the water.

  4. @120 in 20: Interesting. I've also read some people stick some charcoal in their grow bed (@the bottom) just to collect any metals that may be present.

  5. Jeff: Hear ya on the overflow/stand pipe diameters, but I don't see how the overflow pipe could ever be flowing "full" so to speak. I will, however, install a wider stand pipe just so I don't have that come bite me in the arse.

    Good news today: PH is 6.8-7.0. I think by tomorrow it will be down to 6.6. I'm adding a small amount of phosphoric acid mornings and evenings. Well, I'm not - my caretaker at the farm, via cell phone text messages and instructions, is. Can't wait to see how the plants do at this PH range.