Pond with algae & poor plant growth

[tabb77]

I have a pond (20ft X 9ft X 3ft deep) that has been suffering from algae and poor plant growth ever since I re-dug and landscaped it last year.

The Irises in the pond have put on little growth and most of the leaves are yellow. The brooklime is the same and most of the other marginals have put on little to no growth. The hornwort and milfoil are faring better but some of the stems, especially in the shallower water, have been smothered in fibrous alage. Also, whenever you move or disturb the weed, it prouduces a big cloud of green which I also assume is algae. In addition to the fibrous algae & the green cloud producing algae, the Milfoil is coated with what seems to be some sort of green sand/grit- I guess it's algae as well. I tried putting in some new Canadian pond weed a few weeks ago - it is now coated by the gritty green substance and again produces clouds of green when poked. The lilies seem ok. THe water itself is a greeny colour and you can only see a few inches deep. The pond has(had?) 3 very small Koi's in it. Considering their size and the size of the pond i dont think they have had much impact on the ponds water quality.


I have also over the years built three other ponds in the garden, two of a similar size and 1 a lot smaller. Whilst they have had algae in the past they have never had the type that produces the green clouds when disturbed, and plant life has always grown rapidly and healthily. It seems to be that if I remove a plant from the new pond- e.g milfoil- and put it in one of the old ones it improves, but if i put a plant that is growing very rapidly in the other ponds- e.g Brooklime- in the new pond it deteriorates.

I have tested the pond and the levels of amonia, and nitrites were fine and the ph was 8-8.5. The ph seemd high but it was actually higher in one of my other healthy ponds. None of the older ponds have pumps/filters and the new pond has no filter and a very weak pump which is just an ornamental feature; I can't afford to run any powerful pumps or filters so that is out of the question. Since i have managed to acheive some sort of natural balance in the other ponds without pumps/filters/chemicals i hope i can do the same in this one.

I have read algae can be caused by high sun levels (the pond is in full sun) and nutrients but surely that would also make the plants grow well? One of the other healthier ponds is also in full sun.

Does anyone have any solutions or ideas how i could get the plants to start growing properly?

Thanks in advance.

[kaitkaitkait]

If your water is green and cloudy you might want to try this to cut down surface light:

Get some natural cork tiles, cut them into quarters and boil them well to get rid of the natural dye in the cork. You can make lilypad shapes out of it if you like (I did ) and then float them on the pond until your own lilies or surface covering plants can rise up enough to compete.

I still have a couple floating on there even though I've got tons of real lilypads now, but they're nice to rest nightlights on in the evening if we're eating outside.

Other things friends have tried were draping a sheet over half the surface of the pond and weighting it down with bricks at the corners, or begging lilypads from friends gardens which will last for a while before rotting and look rather nice.

[Lancashire Lad]

You haven't given any details of the construction of your pond (i.e. is it a natural clay lined pond, does it have a neoprene liner, or is it constructed from concrete etc.).

By the sound of things you have far too much nutrient in the water. Did you put any soil or other nutrient rich base material in the pond?

Reducing light at this stage, (with a pond full of plants and algae) will be something of a hit and miss affair. You may find that the plants start dying long before there is any appreciable loss of algae.

The cork tile suggestion for reducing light penetration may possibly help, but I'm not at all sure that you might not be introducing further complications here. After all, cork is made from plant material, and plant material will begin to rot in the water, thus making available yet more unwanted nutrients. (Plus there may have been undesirable chemicals used in the manufacture of the cork tiles).

I certainly would not try this: -

Originally Posted by kaitkaitkait

.....or begging lilypads from friends gardens which will last for a while before rotting and look rather nice....

As the lily pads will be rotting, (although perhaps not visibly for some time), from the moment you put them in. again introducing yet more unwanted nutrients.

As we are now progressing towards autumn/winter, I would suggest letting the natural way of things just get on with it. The algae will almost certainly die off during the winter months, giving you less of a problen to deal with next year.

In early spring, before the algae problem gets too bad again, I would recommend floating several nets filled with barley straw. (NB. To work they must remain floating, so including an inflated & sealed plastic bag or some other floatation device in each net is desirable).

As the barley straw slowly rots down, it produces natural chemical "algicides" and encourages the growth of vast numbers of microscopic single celled protozoans which have an inhibiting effect on algae, but have no detrimental effect on higher plants or wildlife. This process, although not a quick fix, (it will certainly take several weeks), is, in my opinion, the best, most natural method of algae control. With no unwanted artificial chemicals, or unwanted nutrients being added to the pond.

There are several web sites explaining the process of barley straw algae control. (Including the Royal Horticultural Society's website).

Regards,
Mike.

[tabb77]

Thanks for the replies.

To answer the questions of Lancashire Lad, the pond was construced using butyl liner and the only things that have been put in are the plants together with the baskets, hessian sacking, aquatic gravel and aquatic soil that they sit in. I also used a few bags of small green slate pieces to line one of the sides of the pond- according to the bag this was meant for "water features" and i thoroughly washed it before putting it in place.

I also tried using a block of barley straw a while ago although it didnt seem to make much difference; maybe i need to use more next spring due to the size of the pond?

As for lilies i currently have 4 in the pond (all cuttings from lilies in other ponds) and together with the hornwort they are covering around a quarter of the surface area. I usually try to remove the dead/dying leaves.

[Kayleigh]

have you got oxygenators in there as you will need quite a lot to keep the water fresh..
yellow flag irises are good too but will need to be in baskets or they will take over.