Top up your pond in dry spells as plants and wildlife soon start to suffer if you allow too much water to evaporate away in the hot weather. Rainwater is best, but tap water can be added little and often without upsetting the pond's natural balance.
While you're at it, take a close look at your fish. If they're gulping for air close to the surface, there's not enough oxygen in the water - quite a common problem on sunny days. In extreme cases, they could die. For immediate relief, spray the pond with a jet of water from a hose. But if it's a regular issue, consider installing a small fountain, so the splashing water can constantly replenish the oxygen in the pond. You'll find fountain kits, pumps and everything else you'll need in our garden centre here in Lymington.
Other summer pond care jobs include thinning out oxygenating plants if they've got too congested, pulling out excess growth with a rake, and checking for signs of pests and diseases. Aphids can attack water lilies and marginal plants - to tackle the problem, simply weight the leaves to push them under the water for a couple of days so that pond creatures can feast on the pests.