Water garden calendar, March. Testing the water temperature

Testing the water temperature.

All fish-keepers will be getting itchy fingers, desperate to feed their beloved pets. The tough old goldfish can take anything you throw at them, but the Golden Orfe and especially the Koi Carp, just cannot be fed until the temperature of the water is getting permanently above 7C (45F).

Then between 7C and 10C(50F) only feed low protein food or wheat germ. It is only above 10C that things really get swinging underwater: oxygenators start seriously oxygenating; bacteria really get down to digesting organic matter and the fish metabolism really kicks into gear.

The last thing the fish need in their delicate state, after several months in repose, is a shower of toxic inconsumable fish food from the pool surface that will sink to the bottom to add an extra workload to the already pressurized balance of the pool environment. Uneaten fish food is probably the biggest pollutant that regularly gets into the average pool, so this months big tip is to arm yourself with a thermometer and a net fine mesh.

The thermometer will give you the go ahead on the right temperature to start feeding. Use a good quality floating fish food that is appropriate for the time of year and feed it in small amounts. Only feed enough that the fish can eat in a minute or two: any that is uneaten, use the net to remove it.

Even if you havent been inundated with frogspawn this may not be a good time to sort out major mechanical problems; wait until the water warms up a little. Many of the occupants of the pool are right down the bottom because that is where the warmest water is. When water drops in temperature below 4C, it changes density and becomes lighter. That is why you get ice on the surface of a pool rather than the bottom. In this way it makes a sort of insulating layer for the lower water and it has to get REALLY cold to affect that. If in order to check that the filter system and pump are working, you need to turn it all on, you may be in danger of churning up the balance of cold and very cold water in the pool.

Not only that if the filter has been turned off for some time and stagnated for more than a month or more, it may have built up a colony of the wrong sort of bacteria within it; something that if it is flushed into a fairly comatose environment would be unable to cope with it and would have polluting effect with dire consequences.

If there are tadpoles, it would be best to refrain from turning on the pump and filter until they are large enough to swim away from the pump when it is switched on, rather than get plastered to the pump pre-filter, or worse, get minced up in the rotor and flushed into the filter system.

These late March tadpoles by now should be strong enough to swim away from the filter pump inlet.

Top Tips for the Month

1.If youve been dragging out that blanket weed all month and hoiking out oxygenating weed along with it, it may be as well to replant a batch of it. Break off some clean pieces from some overgrown stems and push them into baskets in bunches of 5, with 25 bunches to a basket and place it on bricks about a foot below the surface. Once it is obviously growing, you will see fresh dark green growth at the ends of the cuttings, lower it to 2ft (600cm)(see planting oxygenators).

2.You can sort out those marginal plants if they need replanting. No real hurry but get it done before the middle of April. Just empty out the baskets, divide with a knife or spade and replant the portions with healthy growing tips in a good heavy garden loam. Wait a while for the lilies until they are in full growth and use heavy loam for them, the heavier the loam the better. Top off with pea shingle. In new ponds they will need a good feed of a slow release plant food pellet each. (See planting lilies).

3. Keep your eyes peeled for any fish diseases, sores, or things hanging off or on and treat accordingly. (See fish problems)

4. In fact keep a general watchful eye over your precious creation. There is no doubt that regular visits down to the poolside give you an informed impression of how things are developing and enable you spot potential problems before they have any effect on the environment. Its a shame that scientists and politicians are not able to act on informed opinion on a global scale.