A little effort now can result in a summer full of healthy, beautiful fish and plants.
A partial water change is highly recommended as soon as weather – and the thickness of the pondkeeper’s skin – permits. The amount of water removed may be as little as 20% if the pond was well prepared for winter, or up to 50% if there is an accumulation of dead leaves and other debris. 100% changes should be reserved for ponds that contain no fish, plants or other livestock, or that have suffered major losses of the former over the winter.
After the portion of water is removed (by pump or siphon), as much decaying vegetation, fallen leaf material and other debris should be removed as possible. Once warmer weather arrives, these begin to decompose, fouling the water and promoting fish disease as well as algae growth. The addition of a bacterial/enzyme product can encourage the healthy breakdown of the remaining small amounts of debris.
While the water level is still low, every piece of equipment should be inspected for wear and damage, including the liner or preformed pond itself, pumps, filters, lights – and all the cables, tubing and connections involved as well. It may be a nuisance to repair or replace items now, but it can be an absolute nightmare to deal with them in mid-summer when everything in the pond is looking its best.
The pond liner or preformed pond’s overall condition should be assessed. Smaller tears or punctures may need to be patched, and evidence of larger damage or degradation may indicate that it’s time for replacement or upgrading to better materials.
Pumps should be scrutinized for housing damage which could result in electrical shock hazard or, in some models, oil leakage and intake blockage (which can reduce water flow and possibly damage the pump itself). If so designed, the pump should also be opened for inspection of the impeller.
Filters should be cleaned of visible debris that will reduce flow or break down into algae-promoting nutrients. Even “biological” filter media may require rinsing if it has been stored in either dry or stagnant water conditions. Filter pads are best replaced.
Pay particular attention to electrical cords that may become frayed or cracked. At best, these will constantly trip Ground Fault Interrupters or circuit breakers; at worst, they create a shock hazard for both livestock and humans.
Be on the lookout for stiff, kinked or ruptured tubing as well. Any constrictions or leakage will reduce the water flow available to fountains, waterfalls and filters. And while we’re at it, now’s the time to secure with plastic hose clamps all the “temporary” connections we made last year.
Hardy plants that spent the winter in the pond should be inspected as well. Some may have perished or be weakened beyond salvation, and should be discarded before they begin to decay rapidly. If no new growth is visible above the soil, the rootstock should be examined for signs of decay. Others plants may have filled their containers so fully that they need repotting or division. Hardy plants that were wintered elsewhere should be moved to the pond as soon as growth is evident (assuming ice is gone, of course).
Many pondkeepers temporarily move sprouting plants into shallower areas or put them up on blocks to bring them nearer to the water’s surface and life-giving sunlight. It is important to protect any emergent shoots, stems or leaves from frost damage, just as in terrestrial gardens.
Plant foods may be added to potting containers as soon as growth begins. Time-release pellets are preferred in order to prevent “burn” and over-fertilizing of the pond water itself.
Tropical plants should not be added until temperatures are expected to stay within their normal range. Maintain these indoors under lights or in a very bright window.
Fish should be examined at this time as well. Not only are they sluggish enough to catch in a half-full pond, but many signs of future problems may be apparent. Any fish with open wounds, swollen abdomens or red blotches on the body or finnage is best removed to a treatment tank or vat. If most fish appear affected, it is a sign that the pond was not properly prepared for winter, and that much work may need to be done to restore its vitality.
Finally, re-filling of the pond may begin, but not with reckless abandon. Ideally, a garden hose may be left to “trickle” new water in over a matter of hours, or even days. This allows filling to be accomplished with a minimum change in the pond’s water temperature, and allows for some escape of gases from the tap water as well. A dechlorinator should be used if chlorine or chloramines are present in the source water.
Once the pond is filled, circulation and filtration can resume, and biological filtration in particular should be encouraged. As the fish and other animal life begin to produce waste products, it is important to prevent dangerous buildups of ammonia and nitrites. For a small fish load, simple aeration and circulation may be adequate to support the beneficial bacteria that remove these two toxic compounds, but heavier stocking may require the use of a more sophisticated biological filter.
Avoid the temptation to begin tossing handfuls of high protein fish foods into the pond as soon as the fish appear to show interest. There is a likelihood that much of the food may go uneaten, only to spoil, decay, and feed the algae growth in the pond. Floating foods are suggested over sinking, as uneaten food will be more visible and more easily removed.
In addition, fish digestion is very slow at low temperatures, and consuming too much of a difficult to digest food may actually lead to internal bacterial infections, particularly in koi. It is probably best not to feed fish at all until the water temperature is above 55 degrees F.. From 55 to 65 degrees F., easily digested, low-protein foods such as pellets containing wheat germ should be offered, but sparingly. Standard and especially “growth” type foods that are high in animal proteins should be fed only after the water temperature exceeds 65 degrees F.
Additional fish (from storage or new purchases) can be added whenever water conditions in the pond substantially match those of their current quarters. In particular, water temperature should certainly be within 10 degrees F., and preferably much closer. Take care again that heavily fed fish from a warmer environment are not suddenly transported to a pond so cool that it shuts down their digestive system. Other factors that are of concern include pH, ammonia, nitrite and nitrate levels, all of which can be easily ascertained with common aquarium or pond test kits.
An algae bloom is to be expected in most ponds in the Spring, as fish begin producing nitrogenous waste, but plants have not yet grown enough to remove substantial amounts of nitrogen from the water. This natural event is no cause for alarm; in fact, an Spring algae bloom actually helps protect fish from potentially high levels of ammonia and nitrite. If the Spring cleaning was adequately done and the fish are not overfed or overcrowded, the explosion of green water will subside quickly as the plants begin to dominate.