Updates: Andy from Bukit Jalil

Andy has two ponds at his house in Bukit Jalil. He contacted me when he wanted to setup an AP to be hooked up to his ponds so his wife could plant some veges. His ponds are the ones I was talking about the filtration being very efficient at making the ponds crystal clear. Yes his filters have proven to be pretty good until we hooked up the gutter rows which has significantly lower flowrates which the finest of sediments would settle in there.

The exact same problem which we observed in Haji Anwar's setup in Dengkil. Because I've got no experience with gravel beds I could not say if sediments settling in them is a bad thing. Affnan would be the best candidate to answer that! For gutters types (nutrient film technique - NFT) however, sediment settling in them should be avoided at all cost. The reason being the fish matters will continually release ammonia in the gutters itself and it'll be all the plants are going to get. Since ammonia is alkali in nature, pH lockup will occur and make nutrients unavailable for the plants. I've also mentioned before that the trend around the world nowadays is to remove all sediments possible before flooding the AP system, the trend must not have occured without good reasons to do so.

Anyway, Andy quickly solved the sediment problem by constructing a RM 15 solution which is a vortex sediment tank from a small dustbin. You can see some sediments trapped in there. Periodically he will flush this tank and provide the nutrient elsewhere in is soil garden. They do make good natural fertilizers!

Some pictures to enjoy on Andy's test setup which employs rectangular PVC pipes (rainwater down pipe) from Arensi Marley Malaysia which costs RM 62 per piece for a 6-meter section. That is pretty cheap compared to using open top gutters! The only disadvantage I could think of is that the plant spacing is fixed as compared to using polystyrene suspenders which you can adjust by cutting new holes for a new spacing configuration. Nevertheless, it is a very good solution, and yeah they look good too!

Enjoy the photos below! I should be able to post some photos from the Dengkil setup in the next few weeks. Cheers!

The said rectangular pipes with holes cut in them. The size used is 120mm x 80mm

Seedlings look healthy although Andy is yet to throw some iron into his filters. Hope he's done that by this time...

Though his pond looked crystal clear, look at the pile of sediment inside this vortex settlement tank. Typically on a pond setup, this would be a prefilter before mechanical filtration. Bio filtration is usually set at the last stages of a pond filter. This gives me some idea on the setup I'm designing for my place.

Helping Hand: Dengkil AP - The Sediment Catcher

Alright since we've decided to end the era of the solids settling in the gutters, here comes the settling tank!

Before that let's see some better pictures of the pond...after the filter reworking...

 Water is pretty clear but it appears yellowish...before we hooked up the AP system it was much cloudier than this. Since the AP system the particles were being transported to the gutters and settled there...we think that's causing the slow growth we're observing...

The filter appears to be working but time to time it will choke and will need us to make way for the water flow so it doesn't choke the pump. This action will create bypasses in the filter hence making the filter ineffective for solids removal. Nevermind, we will attempt one last try for the filter after we install the sediment catcher for the AP gutters. After all, we need to find out if the growth problems would be solved by the sediment catcher.



THE SEDIMENT CATCHER (OVERFLOW FILTER)

A rough sketch of my overflow filter

How it works?
Water enters the bottom of the tank into a settling chamber then flow up through filter pads. The outflow works on the overflow principle and supplies the water to the gutters. Solids will settle at the bottom of the tank, while the finer ones will be trapped in the filter materials.

Items needed?
- plastic barrel (we used 55gal drum, for smaller applications just find the cheap wastebin)
- pvc fittings
- pvc pipes

How to build it?
Well let me explain the process with some pictures...

Some of the items I've listed...total cost including barrel, pipes, fittings, and filter material. About RM 200

Cut open the top with a jig saw...save the lid

Make the filter material support about midway of the tank. Install a drain outlet at the bottom. Two overflow holes to supply to the gutters. The inlet is about half the height of the space between the bottom of the tank and the filter pads. This empty space is the settling chamber.

Here is the final arrangement, the lid has been sawed for holes and serve as a tray to hold the leca and filter pads. The water enters at the bottom, then overflows into the green basin and proceed to the two overflow pipes (overdesign to prevent mishaps).

Another idea I didn't think of earlier was to use the lid, attach stands to it and just set it inside the tank to make it easier instead of making supports from drilling the drum wall to set the pipes to hold the media, it would also allow us to change the height of its stands if we need to adjust it...too bad the idea came too late after we've drilled 8 holes for the support pipes.

The filtering goes with leca first, then some coarse pad and on to about 3 layers of fine pads. We'll also add some coral grits and some iron on top of the filter pads to supply the good stuff to the AP plants.

We've completed the build of the tank but we couldn't find the time to install it. So Haji Anwar is gonna install it some time this week and I'll update you when I visit him in about 2 weeks.

Problems: Dilemma on growth - solid waste in the gutters

In my previous article on the 'Good Reads for AP' the article did mention that having the solid waste present in the AP system as being a threat to the system. I thought over it and it does make sense especially with gutter type setups. In conventional growbeds where solid wastes are allowed to settle in, the waste would rot, release ammonia and quickly come in contact with the nitrification bacterias hence the ammonia problem may not be as significant. In conventional growbeds you can also add worms to it to help digest the waste but not with a gutter setup.

After a month of running the AP system in Dengkil, the plants doesn't seem to grow well. I figure that the plants may be lacking iron but even so, when I was starting my system the plants wasn't growing as slow as this. Then, referring to the article I read by Growfish about the potential problems with trapping the solids in the grow beds/channels I think I might have found the answer. Somehow, when we ran the system immediately it was laden with solid waste settling in the gutters. At first I thought it wouldn't be critical however after a week the gutters were about half-full with sediments.

Think about it, gutter type system has very minimal amount of media since it is designed to just flow nutrient full water to the plants, not to perform any mechanical or biofiltration. Once you have the solids in there it will settle, where it settles it will rot, and where it rots comes ammonia. What I think is the root cause of the growth problem is the fish poop in the gutters. The gutters have become the releasing point of ammonia where there is minimal flow of water and minimal media to immediately convert it to nitrates. Ammonia, being alkali in nature may affect the pH in the gutters and hence will eventually affect the pH of pond, and high pH is bad for nutrient supply. I might be wrong, but at the moment the water in the gutters though they come after they passed the pond filter, is now passing through solid wastes in the gutters. I'm thinking the plants are being choked by the rotting solids in the gutters.

So if we build a sediment catcher tank which will help the solids to settle and the water filtered to remove the finest particles, perhaps will get back to the good state and solve the problem. The trapped sediments will continue supplying ammonia to the water and may also be removed if present in excess.

This tank is what we intend to build!