Flowers an Flowers

How to combat algae in new pond?

I have just set up a pond that is about ~100 gallons. There is no mechanical filter, only a small pump circulating water.

To reduce Algae in the long term, you need to restrict nutrients and sunlight in the water. It needs both of these in order to grow, as other plants do.

Practically you can achieve this by having some surface plants, such as the Water Lily that you have, which cuts light levels entering the pond. Any other shading would also be useful, anything floating, such as ornaments, does help, or otherwise nearby objects creating some shade is useful. Try not to shade the water lilies much though, as they need bright direct light in order to flower profusely.

To reduce the nutrient level in your pond, there are a few things that you can do that will have a major effect. Remove any debris, such as decaying plant leaves etc, don’t overfeed your fish, as rotting food and fish waste will decay to become nutrients that will feed Algae growth, avoid water run-off from surrounding soil, as this will bring dissolved nutrients with it too.

Waste is processed by bacteria in the water, largely the Nitrogen compounds are converted into nutrients that will fuel green growth. By adding bacteria into your water, you keep this process as even and fast paced as possible, and also improve the water quality for your fish – this is really important, as nitrogen compounds can kill fish. To optimise bacteria levels, you can buy liquid or dried mixes at aquatic supplies stores. Water filters usually contain high levels of bacteria, but you’ve chosen not to use one, so just increasing the water borne levels will help a lot. The product recommended by the pet store employee would be similar to this.

The bacteria will help keep the water healthier, and somewhat cleaner, but will generally be better for improving your fishes health, in my opinion.

There are many types of Algae that colonise ponds, the free floating type, that you seem to have, and another type, called blanket weed, which is long strands of really fine Algae, which clumps together – whilst you may not have this at present, it will likely arrive in future. This is best removed manually, using a cane or similar, and entwining it around.

There are other additives that you can add too, and I prefer to use natural minerals and enzymes to do the job. Nishikoi make a product called ‘Goodbye Green Water’, and there’s a product for Blanket Weed, called ‘Blanket Answer’, both of these are effective and easy to treat smaller ponds, and are natural and safe for fish and wildlife. There’s a link to Blanket Answer here- http://www.allaboutkoi.co.uk/blanket-answer-combats-blanket-weed-p-29755.html and Goodbye Green Water here – http://www.koibitz.com/Scripts/prodView.asp?idproduct=378

If you use a natural product such as these, your pond should improve within a couple of weeks, and this will be more effective than just bacteria alone.

Even if you don’t have a built in pump, you could also consider a small portable filter, which will help oxygenate the pond, as well as process waste more quickly, and these can cost just a few dollars, and would help make a difference too, as they remove larger pieces of debris and clumped Algae. (There are products which help the Algae clump, and thus become filtered out, but I’ll make no further mention, as your current choice is not to have a pump, but worth considering if you ever get one).

Water snails also eat Algae, these may appear naturally, but if you could add some, these will help speed up the clearance.

On an ongoing basis, just remove any plant debris as it occurs. You could consider adding some more submerged oxygenating weeds, which will improve the water quality for your fish. As water gets warmer, it’s naturally less able to retain dissolved Oxygen, so these can be a lifesaver in summer. (A pump or filter would increase Oxygen absorption too).

Hope this helps. Good luck! Rob

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