Info & News Archives

Garden ponds

Copper ionizers for hair algae control: do they work?

Aquaculture

Artemia largely replaced in fish larval feed

Freshwater crayfish growth rate greatly increased

Garden Ponds

Copper ionizers for hair algae control: do they work?

Only a couple of years ago, copper ionizers hit the market. The principle is sound: copper is toxic to hair algae, also known as blanket weed and string algae, at concentrations as low as three parts per million . Above this concentration copper is toxic to fish so the ionizer has to keep the copper level in the water within a narrow range around three parts per million.

However, copper is toxic only in its ionic form and copper ions readily precipitate out of solution at pHs above 6.8. To work efficiently, the water either has to be kept at a pH below 7 or the water leaving the ionizer has to be rapidly distributed throughout all parts of the fish pond via a number of outlets. Ideally, the pH should be kept down and a network of outlets should be installed in the pond.

All of this is theory. What has happened in practice? Some claim the ionizers don't work (especially if ponds have pHs up near 8). Other complaints include the lack of battery back-up: the slightest pause in the supply of power turns them off. Finally, the units are expensive but fragile.

Ideally, copper ionizers should have sensors near the outlets in all parts of the pond with direct feedback to the ionizer. The release of copper ions should be automatically adjusted to each individual outlet to keep the concentration over the whole pond within the required limits. Too sophisticated for the average garden pond? Perhaps, but one day soon copper ionizers may become the solution to that scourge of the water garden - blanket weed.

Anyone with experience, good or bad, with copper ionizers, please email me at: info@fishpondsolutions.com

Aquaculture

Artemia largely replaced in fish larval feed

Researchers have succeeded in replacing up to 90% of the live feed in fish larvae diets. Artemia cysts, the only reliable source of live feed for fish hatcheries, will grow in cost as the world demand outstrips supply. Reducing the proportion of artemia necessary in fish larval diets is a major step forward for aquaculture.

Selective breeding has doubled the yield of marron (a large Western Australian crayfish) potentially increasing profit up to nine-fold.

The information in both the above news items were from the Fisheries R&D News, vol.14, no.1, Feb. 2006. More details on the above may be found at: http://www.frdc.com.au

Environment

Global dimming

Recently a TV documentary I saw questioned whether reducing some forms of atmospheric pollution was actually contributing to global warming. Pollutants from hydrocarbon fuels were said to be causing global dimming, reducing the severity of the greenhouse effect. The greenhouse effect is caused by the carbon dioxide from the fossil fuels. Unless the carbon dioxide was reduced along with the other pollutants, global warming may actually be accelerated by removing the other pollutants. In other words, the greenhouse effect is being masked by the other pollutants and is potentially much worse than was thought.

I have been blaming global warming for the increase in nuisance algae in ponds. Now, I'm wondering whether, in the near future, we will have any water for the algae to be a nuisance in.

Whale slaughter

Certain Japanese companies continue to slaughter whales under the farcical premise of "scientific research". Whales are not only in danger of extinction, they are highly intelligent, possibly as intelligent as we are and certainly as intelligent as a child. I presume they are therefore extremely sensitive to pain and are as terrified of death as a child is.

One excuse a Japanese spokesman gave for continuing whaling was that the much of the world was telling them to stop doing it. It was a matter of pride. Personally, I believe it is a matter of money.

Governments continue to turn a blind eye to the Japanese whalers. After all, it might cost us money in trade if we upset the Japanese too much.

What can we do to convince the Japanese that they don't really need to slaughter these magnificent animals? The only thing I can see working is to boycott Japanese goods. We need to hurt the pockets of Japanese companies which have more influence on the Japanese government than the whaling companies have.