Water Garden FAQs

Questions arising from water gardening are enormously varied. They reflect the novelty of the subject rather than any inherent difficulty, and reveal uncertainties more often than real problems. Apart from the omission of any to do with green water, blanketweed and fish disease (which are, I hope, covered adequately in the general text), the following represent a typical selection of the wide variety that have been put to me over the years.

Water Lily not Flowering

I have had a water lily for three years which produces healthy-looking foliage but so far has not produced a flower. Could it be a blind plant?

The possibility of a blind (non-flowering) plant is remote, since named hybrid lilies are propagated vegetatively from stock of known flowering potential. Non-flowering could be due to the failure of the water to warm up in the summer. A continuous flow of water through the pool, particularly cold spring or mains water, or a heavily shaded pool would produce this effect. Another possibility is excessively deep planting. If the lily is in deeper water than suits that particular variety, it may have to devote so much of its strength simply to getting its leaves to the surface to survive, that none is left for the production of flowers.

Gulping Fish

Several times recently (generally in the morning, but on one occasion all through the day) my fish have been mouthing at the surface as if searching for food. When I put food on the water they ignored it. Two golden orfe, which I have had for ten years and were about 18 in. long, were found dead but showed no sign of disease or injury. The smaller orfe and goldfish (about 30) are now feeding and look healthy. The pool is 10 ft. square and there is obviously nothing wrong with the water which is perfectly clear and healthy. What is the trouble?

First let me emphasise that the appearance of the water is no guide: however clear it looks, it can contain bacteria, viruses, and a host of other tiny organisms completely invisible to the naked eye. It is obvious, however, that the trouble here is not disease, but severe oxygen shortage. This can occur, even in a well-planted pool, during periods of close, thundery weather. The phenomenon can be of very short duration and often causes no more than temporary distress to the fish, shown by a gulping of air at the surface. The effects are most severe in the latter part of the summer when the activity of oxygenating plants is declining, and of course at night when the plants do not produce oxygen at all. That is why casualties usually occur overnight. Golden orfe are much more sensitive to oxygen deficiency than the carp family (goldfish and shubunkins) so that the latter may survive conditions that are fatal to orfe. The bigger they are the more oxygen they need, so that the finest specimens are the ones which are likely to die first.

Big orfe need a larger pool than this, well oxygenated by fountain and/or waterfall arrangements as well as plants.

Fishing Cat

My neighbour’s cat spends hours crouched at the edge of my pool watching the fish. It hasn’t caught any yet but it is very worrying. Is there anything I can do to protect them?

Cats, though fascinated by fish movement, are seldom a real danger. Having dabbed a tentative paw and found that the water is wet, most are content to be fish watchers rather than catchers. However, the odd one that does persevere can become a real menace once it acquires the knack of hooking a fish out. Such individuals have to be convinced that the pool is a place to be avoided and the necessary short, sharp shock-can best be administered by approaching the animal while it is absorbed and giving it a nudge just firm enough to tip it into the water. The animal will suffer no injury, except to its dignity, which in cats is a very sensitive area.

If you are unable to adopt this method because of misplaced sentimentality or because you cannot get close enough to the cat, the best alternative is a well-aimed dishcloth well loaded with water. A direct hit is not essential: the spray of water from a near miss can be quite effective.

Unconventional Pools

I have an old galvanised tank 4 ft. square and 4 ft. deep, and also an old domestic bath which I would like to use as garden pools. What can I use to paint them to protect fish and plants from the effects of rust and the galvanising on the tank? Can you recommend suitable plants’?

A few patches of rust will do no harm and a used and weathered galvanised tank presents no dangers to plants or fish, so there is nothing to be gained by painting them. Both receptacles are badly proportioned for use as pools. The tank is far too deep and would require the insertion of a timber frame with planks to support containers of marginals at a depth of 9 in., and of a lily and eight oxygenators at not more than 18 in. Thus 2{ ft. of the 4-ft. Pit you will have to dig to sink the tank will be wasted labour. Surely the small cost of using a PVC pool liner instead of the tank would be more than offset by the advantage oi having to dig down only 18 in.?

The average domestic bath at least has a suitable depth, but it needs very careful finishing with a surround of crazy paving and lip-draping plants to make it look anything other than what it is. With only about 10 sq. ft. of surface area your choice of a lily must be limited to small growers such as Joanne Pring or Froebeli. Alternatively you could use One each of the miniatures, Nymphaea pygmaea alba and N. p. helvola, provided the containers were propped on bricks to make the e.w.p. 6 to 8 in. Haifa dozen oxygenators and a similar number of small fish would be ample for what is more like a large aquarium tank than a small garden pond.

Disappearing Floating Plants

Last year I introduced frog-bit and fairy floating moss into my pool and they spread well during the summer. By the time I cleaned out the pool in the autumn the frog-bit had disappeared. I carefully netted off the floating moss and then returned it after refilling the pool, but it disappeared during the winter. There is no sign of either this year. Aren’t they supposed to reappear every summer?

They are, and they do, but your too-thorough clean-out has interrupted their growth cycle. Hydrocharis (frog-bit) produces resting buds or ‘pips’ at the end of the summer. These, sinking to the bottom, are the only part of the plant that survives the winter. They rise to the surface in the early summer and produce the new generation of plants. Azolla (fairy floating moss) also dies off with the arrival of cold weather and renews itself from bottom-resting spores in the summer. You threw out the overwintering parts of both plants with the mud and so prevented renewal. Another reason for limiting autumn work to general tidying, and doing a full cleanout only in the summer when you can see what needs saving.

Dangers from Copper

I was planning to use copper pipework for my fountain installation but have been warned that the copper will poison fish. But I see that the fountain ornament I have purchased has a copper pipe running through it from the base to the jet mounting. Does this mean that it is safe to use copper?

While copper can certainly be highly dangerous to fish I feel that the risks are sometimes greatly overrated. An essential consideration in assessing the danger is the amount of copper in relation to the volume of water it affects. The larger the amount of water the less will be the concentration of copper. One of the few cases I have known where fish losses could be attributed with any certainty to copper poisoning concerned a not-very-large pool into which water drained off a large copper roof through copper downpipes. Such an arrangement invites disaster, and so would the use of copper tubing for the delivery pipes to an extensive system of fountains and waterfalls. I cannot see any virtue in copper for this purpose. Plastic tubing would be easier to work and much less expensive as well as being safer. At the other end of the scale, a foot or two of copper in a fountain ornament is not likely to create problems, as the widespread use of such ornaments has demonstrated. If you want to be really careful you could delay the introduction offish until the fountain ornament has been in use for a while, and there has been one change of pool water. What little danger exists will be considerably reduced by a few weeks’ use.

An Ornamental Duckpond?

Two mallard ducks spent a day on my small fishpond recently and this has made me wonder whether ornamental waterfowl can be kept in a suburban garden. Can you recommend any types that could be kept without danger to garden plants and to fish?

Ducks don’t need a large area of water. A pool of 40 to 50 sq. ft. would be ample for one pair of birds, but they would require in addition the freedom to roam over about three times as much ground area. Among the most attractive and easily kept smaller varieties are carolinas, mandarins, wigeon and Chilean teal. They will probably do little damage to the garden, and certainly none to fish, but in other respects their habits as residents of the garden pool leave much to be desired. They eat plants and snails and insects. They will quickly demolish the succulent growth of oxygenating plants and the choicer marginals, leaving only the coarsest growing reeds and rushes. They will manure the water steadily, producing a thick pea-soup greenness that, with the oxygenators destroyed, there is no hope of improving. They will make the pool surrounds pretty messy. I wish it were otherwise because I like ducks, but I have to tell you that you can have ornamental wildfowl, or you can have an attractively planted ornamental fish pond, but unfortunately you can’t combine the two. If the mallai’d return and show signs of settling on your pond you will have a choice to make.

Loss of Water

I have a large rock garden with a pool at the bottom and another at the top. Water is pumped from the lower to the upper pool, and then it runs back through a series of concrete streams and cascades. When the pump is working the water level in the bottom pool drops quickly; when it is off the top pool is only half full. What is wrong?

Clearly you have a leak in your top pool, which will have to be found and repaired. In addition you may be losing water in the stream section as a result of its movement, in splashing and dribbling over the sides, running back under pouring lips, and perhaps overflowing the sides and corners of the stream section underneath the waterfalls. These apparently insignificant dribbles and trickles can add up to an appreciable loss if the system is in continuous operation. You could check on this by making a close eye-at-ground-level examination when the system is working. The trouble with the bottom pool is probably not a leak but the fact that, when the pump is started, it takes half the water from the bottom pool to fill up the top pool and the rest of the system before there is any return of water to the lower pool. It is essential in any water circulation arrangement that the bottom pool that forms the reservoir should be amply large enough to fill the pipework without a significant drop in level, and that the other pools and channels in the system should be leakproof and hold all their water when the pump is not working.

Disappearing Fish

Five goldfish about 5 or 6 in. long disappeared completely from my pool overnight. I have been told a heron must have taken them but I have never seen one in the area, which is heavily built up. If you think a heron is a possibility what can I do to protect the remaining fish?

A cat would leave some remains and would never take so many at once. A heron must be the culprit, and it is not such a rare occurrence in a built-up area as you might think. The heron operates very early in the day, and is gone before most people are awake. Its favourite fishing position is standing in water up to 12 in. deep and this can be prevented by covering the pool with plastic garden netting. Unfortunately this creates problems for the plant growth as well as for the heron, and if the netting is allowed to sag below the surface to make it less of an eyesore it may impede the growth of lily foliage.

A naturalist who has made a close study of herons maintains that they always step into water from dry land, and this has suggested to some that a single trip wire round the pool is all that is needed to prevent a heron from getting into the shallows. I believe that the wire need not even be visible. A hunter of herons wrote a very long time ago (concerning tech-niques of snaring that would be frowned on now) ‘. . . colour your line of green, for the heron is a very subtle bird’. I have a feeling that the unexpected contact with something not seen is what would frighten the bird. Nylon fishing line of about 8 lb. Breaking strain ought to be both strong and fine enough for the purpose, and it could be strung around the pool and zig-zagged across the shallows without interfering with plant growth. It has the extra virtue of being cheap.

Rearing Daphnia

I netted some daphnia from a farm pond and put them in my pool hoping that they would breed and form a steady supply of live food for my fish, but they were eaten so fast that they disappeared altogether. Is there any way of rearing them so that I can always have a live-food supply handy?

It is possible to rear daphnia in a separate tank or small pool, which should be in a sunny position so that the water will warm up early in the season. The ideal arrangement calls for two separate tanks, one for the daphnia and the other for their food supply. Encouraged by an occasional handful of lawn clippings, shredded lettuce leaves, and similar easily broken down remnants from the kitchen garden, the water in the food-supply tank will rapidly become thick and green, a nourishing broth of microscopic plants and infusoria. A sprinkling of dried blood will make it even richer, but it is not essential. Every day during the summer about a pint of the green broth should be poured into the rearing tank, where the daphnia should thrive and multiply. The level of the food-supply pool must, of course, be topped up daily with fresh water.

One thing you must be very careful about. What ever net or container you use to transfer daphnia from the rearing tank to your fish pond must never be dipped in the food-supply tank. Even a few daphnia accidentally transferred would increase prodigiously and soon consume the entire food supply.

Fish Fry in Winter

My goldfish and shubunkins have produced a lot of fry that are now an inch or more long. Is it safe to leave them in the pool or should I transfer them to indoor tanks for the winter?

This is a very tricky question indeed, and I am not at all sure that I know what, for you, would be the best answer. It must depend, I think, on whether you have serious ambitions to be a fish breeder(and areprepared to serve what may prove a difficult apprenticeship) and whether you can accommodate – or dispose of-large numbers of fish if you successfully rear them. Most pond owners, while delighted to be able to boast ‘home-grown’ fish, are happy enough simply to have the pool kept stocked to its natural level. If you belong to this majority I suggest you leave the fry in the pool. They will run some risks there, but transferring them to indoor tanks can have serious hazards too.

Fish fry are extremely delicate organisms, apt to die in droves from a variety of causes or from no apparent cause at all. Overwintering indoors can only be successful if the fry suffer no sharp change of temperature when moved from the pool to the indoor tank, and no fluctuating water temperatures once they are there; if they experience no considerable change in the chemical content of the water; if the tank is well oxygenated; if the fry are fed with sieved hard-boiled egg yolk or other suitable fry food; if the tank is not overcrowded; if the tank is kept scrupulously clean; and if the water remains free from any taint of decaying food remnants (particularly sieved egg yolk)..

Granted all this, success is by no means certain. With all the conditions apparently in their favour it is still possible – and not at all unusual – to find many of the fry floating dead in the tank, or lying listlessly on the bottom. It has been said that a sick fish is a doomed fish. It may not always be true of adult fish but it is certainly true of fry. Once they have begun to go wrong there is no treatment of any kind that will help them. It is also,- unfortunately, hardly ever possible to make even an educated guess (unless there is some obvious water pollution) as to the cause of the disaster. The only thing to do is to clear out the tank and set it up again and have another try, hoping for better results next time. The better luck may well come, with more experience; the exasperating thing is that it is seldom possible to point to any difference in the conditions, or the feeding, or any other factor, between the tank that succeeds and the one that does not.

In ,a creature which produces thousands of eggs from one pair of adults, a high wastage rate among the offspring must be regarded as normal and natural. If such losses are to occur it seems to me that, for the majority of pond owners, it is better that they occur in the pool where at least they will not be so dis-tressingly obvious. I suggest, therefore, that the fry be left ill the pool where there is a reasonable chance that as many will survive as the pool can accommodate, particularly if there is a pool heater to take care of any ice that may form.

Gravel and Pebbles

Do you recommend gravel or pebbles as a covering for the floor of the pool? No. They serve no useful purpose and it is an illusion to suppose that you will, for long, have a nice clear view of a lot of clean shining pebbles on the bottom. They will rapidly become so camouflaged by a film of sediment as to become invisible. A more serious objection is that drowned worms and other decaying oddments may settle between them, beyond the reach of scavenging snails and fish, and that could be bad for pool hygiene and the health of the inhabitants.

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