At the start of the journal, I mentioned that I am following (more or less) the pond keeping principles of Ada Hofman who is known in Holland for advocating the use of oxygenating plants instead of filters in order to achieve clear pond water. I will post more another time but one of her basic principles is that enough plants must go in within 24 hours of the pond filling up.
Using lots of oxygenating plants to help keep algae at bay is of course something lots of us do already in our aquariums. When setting up a tank I try to pack it with plants from the outset, especially fast growing ones which can always be removed once the slower growing plants have taken off. With my ponds, I really wanted to try to do the same. With the ponds sited in full sun and set up during the height of summer, I felt it was even more important to get as many plants in there as possible from the outset. The challenge of course is the huge amount of plants that would be required. I could not really afford to buy the quantity needed of those small bunches of oxygenators in order to achieve the same effect. To get around this challenge, I had made contact with the owner of a fishery whose lake was filled with hornwort. I was told I could come and help him ‘weed’ the lake and take however much I needed, which was great and solved that problem.
The pond build took so much longer than expected and by the time I tried to make contact again with the fishery, I could not get hold of the person I spoke to. With the clay sides of the ponds crumbling away under the hot sun, I needed to get them lined and filled asap and could not wait for my free pond plants to become available. At first, I was amazed at the staggering amount of spare hornwort, Elodea and Vallisneria I was pulling out of my little mini pond and the tubs on my patio. Incredibly, I would say it was enough to stock the first two smaller ponds we had completed.
By the time the middle pond was nearing completion, I had still not heard back from my contact at the fishery so I ordered 200 bunches of milfoil online to tie me over in the meantime. The milfoil arrived a few days later but in a sorry state, possibly the parcel had been out in the heat for too long. Most of the bottom part of the stems had melted. Normally I would have sent them back but desperate for more plants to go in straight away (especially in the full summer sun), I removed the soggy stems and planted the tops which still felt solid. All I could do was thin out the plants from the first two ponds and share among all three, along with the new baskets of milfoil. As about a week and a bit went by, the water started turning green:
By now, I was not feeling good. The project was costing me so much more time and money than anticipated. The sides of the holes for the large ponds were crumbling away and the ponds that had filled up were turning green and the water was getting darker by the day. There was no going back yet I began to question whether I actually had the knowledge needed to take this on. I double checked her books and green water was definitely not part of the ‘Ada Hofman’ plan. At least not the type of green water I was experiencing in the middle pond – dark green with lots of bubbles;
Middle pond, 6 August
All I could read in Ada’s books was that if you follow the correct steps, you should not get green water. Not the pea soup type. If you do, and if it does not go away, then her only advice is to empty and start all over again! Now I was in desperate mode. It was the start of August and the sun was shining hard on the water. Probably the worst possible time of the year to be at this stage of my project. My Dad and uncle in Holland both have ponds and each sent me over a packed box of oxygenating plants. Still I needed more as the back pond was not far from completion and this one was bigger than the other three combined. I tried buying daphnia but all the stores locally had sold out. I ordered some online but with the heat there was practically nothing left of them when they arrived. The milfoil I had planted had almost completely melted away.
By now I had started going out on my bike and with my net, searching for ponds or waterways with oxygenators and/or daphnia. I felt I needed large amounts, of both or either, in order to save the day. For the first few trips I did not have much luck. Then I struck gold.
Outside some houses I spotted a pond totally and utterly choked with Elodea and I was allowed to take what I wanted. I made a few trips back and forth and in total collected 6 bin bags full. All ponds received a generous helping and by the time the large pond at the back was being filled, I was chucking in armfuls of the stuff.
In the meantime, my replacement daphnia had arrived, alongside shade netting I had ordered. With large poles and lots of string, we made a construction so that each pond could be shaded out with the 50% shade cloths for at least part of the day.
One morning I woke up and decided I was just going to empty the middle pond and fill her up again but this time with plenty of oxygenators. When I looked into the water it seemed like I could see down a bit more than before. I was not 100% sure so I waited to see if there might be an improvement. The next day, yes, definitely an improvement. By day three, I could see the first shelf again. My confidence was restored.
From here things were looking up. My contact at the fishery got in touch and invited me round one evening and told me I could help myself to whatever I wanted. Apart from hornwort, this beautiful lake was also packed with Water soldier which the owner was also keen for me to take. I did restrain myself but still packed a solid bag. Having already filled the ponds with Elodea, I only took a modest amount of hornwort in the end. Just to be safe, as these plants came from a fishery,
I disinfected them all before adding to the ponds.
So the final two ponds had plants and netting from the very start (start and mid-August). At first I just chucked in all the plants and then spent what time I could planting up pond baskets with Elodea, anywhere from 5 to15 in one evening. Also, by this time, I had daphnia blooms in my other ponds so could seed the new ponds with generous amounts of daphnia at regular intervals (not knowing at what stage they would actually take hold in a new pond). The water in both these larger ponds remained crystal clear. Then about 4 weeks after they were filled, a green film appeared over the water with bubble ‘spit’, gradually thickening into a floating, slimy layer.
At first, I was concerned that this could happen despite the many plants and netting in place from the start. When I looked into it further, I read that it was to do with protein bacteria or something but definitely not algae. I skimmed off what I could with a net, which made a difference for a day or so but the it came back. After a few more days, however, it just disappeared and everything was clear again.
Although not a pretty sight, I will leave the netting in place (rolled up over winter) until late spring next year, to give the oxygenators a head start over the algae. Hopefully after that, with marginal planting and pond lilies more established and casting shade of their own, the netting will not be needed any more.
Having built a few ponds in succession, it is so interesting to observe the phases they go through. First the mosquito larvae infestation (I was scooping net loads out the size of tennis balls, can you imagine if I let them hatch?) - definitely the favourite stage of the fish in my tubs. Then the green water. And then, crystal clear water with a second windfall (daphnia) for my tub fish.
I know there is a lot more hard work ahead but after months of toil and stress, now that the ponds were finally planted and clear, at last, the garden was starting to give me back some moments of pleasure. Actually, of sheer excitement.
Middle pond, 8 September
.Thelypteris palustris, a fern as a marginal plant.
