Hydroponics & Mating

I've moved the watercress we brought back from Pembrokeshire out of the bottom filter box as it was too constrained and moved it to a proof -of-concept hydroponics setup I cobbled together from a piece of guttering I got from B&Q for £8.

I placed the filter box outlet over one end of the guttering and put an end-stop on the other end. Without the end-stop there's a danger of everything being washed out of the guttering. A couple of small drill holes at the far end allows a continuous flow of water along the channel with most of it overflowing over the top of the guttering. The watercress sits in the Alfagrog I had in the bottom box. Naturally, the gutter had to be slanted in the right direction to prevent the water backing up, but not too much that it creates a kayaking slalom course.

In the photo below you can see the white guttering running from the filter box along the top of the gabion baskets. The pool liner runs behind the gabions so any overflow runs back into the pond.

The Alfagrog is all bunched up at one end, as I didn't have enough to fill the entire channel, but I can easily add more, or use gravel.

Rather leaky and make-shift, but it works. What I really need is to place the filter box at a height and have a cascade system in which I can place the growing media, which could be traditional hydroponics beads, or the Alfagrog I'm currently using. Both are extremely porous and will house colonies of beneficial bacteria to help clarify the pond.

Here's a video of a simple cascade system:

I've ordered 3 x 20ltr buckets with lids from a seller on e-Bay, along with 40 litres of clay pebbles. Should arrive some time this week. 

Each thing I do in the direction of clarifying the pond leads to another idea. Perhaps I should consider incorporating a kayaking slalom course and delay completion even further.....

The sheep's wool filter box is working better than expected and has a large algae capacity compared to the sponge filters, meaning the wool doesn't need to be wrung out anywhere near as often. The fine sponge filter needs wringing out some 2 or 3 times a day, whereas the wool needs changing no more than once a week.

Given how efficient my Heath Robinson affair is (I can see the bottom of the pond in the 2m deep end), I'm starting to have 2nd thoughts about using the huge filtration vats I inherited - they're overkill and more suited to a pond one may wish to keep crystal clear, which I don't.

The other day I spotted a couple of the kio engaging in mating behaviour and took a short video:

There is one large koi - the original, two slightly smaller ones which were added from my father-in-law's pond when he tired of looking after then, two even smaller ones which were probably hatched last year, 25-30 even smaller ones (including fully 5 black ones) hatched this spring and at least one really teeny one which must have hatched in the last month.

One has a deformity of some description, as it's continually swimming upwards and the second it stops it drops to the bottom like a stone. Can't see that lasting much longer.

The video shows one of the two additions being chased by the one from last year - probably its own progeny (koi don't recognised familial relationships, which can cause inbreeding). The chasing and rubbing alongside is typical mating behaviour, triggered by pheromones, and continues until the female spawns. The male then fertilizes the eggs with his milt. The two other long-time residents don't seem at all interested. The eggs and newly hatched fry are very susceptible to being eaten by other koi, including their own parents.

He lost his prospective mate for a while and he reacted by momentarily chasing every fish in sight for a before finding her again and sticking to her.

With over 30 unsexed koi now resident, we're going to have to take more than half out and given them away. Here they are shoaling.

Unfortunately I found a minced fish in the filter two days in succession last week. I'm going to have to put some kind of cage over the inlet pipe to prevent that happening again.