Caring For Your New Water Garden

Caring For A New Water Garden

Plant Care

Most aquatic plants are hungry feeders and appreciate a good supply of nutrients throughout the growing season. An initial application of a slow release Aquatic tablet in May is always recommended. A second application of fertilizer tablets about July 15 will do a good job for most of your plants. Tropical lilies and especially lotus will benefit from applications about every 4-6 weeks during the summer. Waste from fish will provide supplemental fertilizer during the season.

One exception to this fertilizing program are any potted submerged plants such as anacharis and camboba. These plants draw their nutrients directly from the water and should not be supplied with additional fertilizer!

Any spent flowers and yellow leaves should be pinched off near the base of the plants on a regular basis. It is normal for water lilies especially, to shed older leaves throughout the season.

Some submerged water plants (i. e. hornwort) do not produce roots and are simply weighted down to the bottom of the pond with lead weights or stones. However, others (i.e. anacharis) need to be placed in a small pot with field soil or a mixture of sand and field soil (no potting soil) in order for them to flourish. The pots should be topped off gravel/stone etc., to prevent fish from digging into the pots and disturbing the soil. If the tops grow too large and come to the surface, they can be pinched off as needed to control their size.

If koi are being kept, use larger stone (that the koi can’t move) or place a small piece of screen over the top of the pot. If your fish are persistent and continue to pull, play (and eat!) your young submerged plants, it may be necessary to try a less palatable variety (hornwort is the best option). If all else fails, a screened cage placed over the young submerged plants will usually do the trick.

Submerged plants should be kept at a depth of 18-30”. If you are adding submerged plants to a pond with murky, cloudy water, place them close enough to the surface to receive light. Then, as they grow, gradually lower them to the recommended depth.

Aquatic plants are generally very aggressive growers and need to be divided and/or repotted every couple years on average. Water lilies and lotus in particular will benefit from larger pots (and additional fertilizer). Dividing for most bog plants is simply done with a sharp knife in spring or summer in the same way you would do other perennials such as daylilies, iris, etc. Hardy water lilies can be divided from mid-April till about August 15. Lotus should only be divided in early spring before any new growth starts. Field soil (yep, good old Ohio clay!-no potting soil) is considered the best media to use (topping off with gravel etc.). Choose pots wider than tall for best results. Pots specifically for aquatic plants can be purchased for convenience. Ask for a copy of our handout on growing and dividing aquatic plants for more details!


Fish Care

Refer to the page titled ‘stocking your new pond’ in your Project Estimate Binder for recommended fish quantities for your size pond. As they grow (and spawn!) it may become necessary to find some a more spacious home. We would recommend common goldfish, black moors, shubunkins or a variation on the common goldfish for a beginning pond. Japanese koi are large growing fish that do not adapt well to small water gardens, and have special care requirements. Please ask for more information if you would like to include these colorful fish in your water garden.

Your fish will require little food the first few weeks. Try feeding them about the same time 3-4 times a week but remove any food not consumed within 10 minutes. Do not be surprised if it takes your fish a few weeks to come to the surface at feeding time. Stop feeding whenever water temperatures drop below 45-50 degrees (usually about late-October). Always keep in mind, feeding fish is optional as long as your pond is not heavily overstocked and has a full compliment of plants. There is plenty of natural food in the average water garden for your fish! In fact, if you are having excessive algae growth in your pond, one of the best recommendations is always to back off on feeding your fish!


Pump & Filter Care

Generally, most ponds should have two filters. First, a pre-filter which is primarily responsible for keeping the pump running smoothly, but has little to no affect on water clarity or the health of the fish. A pre-filter only needs to be cleaned when there is a noticeable reduction (25% or more) in the flow of the water through the pump. If your water is clear and the flow is good you do not need to clean the pre-filter even though it may look clogged. Pre-filters with foam can be cleaned by pulling the foam out and rinsing it in a bucket of pond or well water then reinserting it into the filter. Pre-filters consisting of a simple cage only require occasionally removing of excess leaves, debris, etc., that may collect on the outside of the cage. Cleaning should only require 5 minutes, once a week!

The second filter, the bio-filter which usually serves as the main filter for the pond and is often incorporated in a waterfall or stream. You bio-filter is responsible for breaking down fish waste, keeping the pond safe for fish and finally, if adequate size, for keeping the water clear. Bio-filters must run 24 hours a day April through October (in Ohio,) whenever water temperature is above 50 degrees to be effective! Even a few hours of a power stoppage can cause the “good bacteria” that lives in your bio-filter to start to die. It takes several weeks for the bacteria to replenish itself after a power outage of more than about 8 hours.

A properly sized, gravity -fed waterfall filter is only required to be cleaned once a year in the late fall or early spring when the bacteria living in the filter are dormant. Cleaning is done by first, removing the filter media (usually lava rock in mesh bags) and foam (if used) from the top of the filter. Clean both thoroughly with a hose (dipping bags of lava rock into a large tub of water works well). Next, clean any debris/sludge that collected in the bottom of the filter tank, returning the media (lava rock) and foam to the filter in the same order it was originally. Some filters may also have an drainage hose attached to the bottom of the filter, to aid in cleaning. If your pump hose feeds in from the top of your filter, make sure it runs all the way to the bottom (under the layers of foam and media). Adjust the bags of lava rock so that there are no gaps along the sides of the filter tank for water to pass by without first flowing through the media.

A backflush or drainage hose can be added to most waterfall style filters if desired. By occasionally turning your pump off and opening the drainage hose, you can backflush your filter during the season to improve efficiency. Backflushing shouldn’t be necessary however, unless the fish load is high or the filter undersized for the pond.

Pressure filters, are another option which provide better polishing of the water  than traditional waterfall filters, but will require closer attention during the season since they do require back-flushing regularly to operate at full capacity. An advantage of pressure filters is they can be positioned away from the pond,  and return the filtered water to the pond even uphill.

Your pump should run 24 hours if you have fish to keep the water clear, well oxygenated and your bio-filter functioning. This is especially important during hot summer days. If your pump stops running or has a reduced flow clean the pre-filter and check all connections for debris blocking the intake or outlet of the pump. It may be necessary to remove the outer case and clean around the pump impeller on an occasional basis.


Heat Control

Consistent water temperatures above 85 degrees can be detrimental to fish and plants. During extreme heat spells (90 degrees +) it is best to partially shade  small or shallow water gardens (under 300 gallons) during mid-afternoon. As a precaution, placing a tarp, piece of shade cloth, etc. across the pond will help reduce the water temperature.  


Algae Control

There are two basic types of algae that can occur in most ponds. Single cell, free-floating algae is the most common cause of green water in ponds. Your water garden may go through a “green pea soup” phase before your plants become well established. This is normal, harmless to fish and plants and will clear up as your plants grow and absorb the nutrients the algae needs to survive. Do not drain your garden and put in fresh water, it will just repeat the same green water phase until a balance is reached! Once balanced your pond should remain clear enough to see near the bottom of the garden at least 10-11 months of the year.

To speed clearing of the water add more competition for the algae (more submerged or floating plants), reduce the number or quantity of fish (fish waste is a natural fertilizer for algae) and remove any plant and leaf debris that has collected in the pond. Limiting fish feeding to once or twice a week (if at all) will also help since the fish will forage more thoroughly for other food sources that may otherwise add to the debris in your pond. Make sure any food that is not eaten in 10 minutes is removed. Weekly applications of beneficial bacteria such as Hydror-Bugs or Green-be-Gone can be very effective. We do not recommend the use of any commercial algaecides since they are often detrimental to the eco-balance of your pond. Remember the two most common causes of green water in any pond are: #1) too many fish being fed too often; #2) lack of leaf control in the fall!

The second type of algae you may see is commonly called string algae and grows along the side of the pond, usually attached to rocks, pots, or the liner itself The thin green layer you will see form on rocks and the sides of your garden below water is normal, desirable and a sign of a healthy pond. If string algae becomes excessive, stop feeding your fish and follow the other steps outlined above. It can also be manually removed with a small leaf rake etc., or the addition of some snails such as Trapdoor or Black Ramshorn may be helpful. String algae is most prevalent in the spring and fall during cool weather but normally subsides in the summer. If string algae continues to be a problem, there are a couple of relatively new products (PondFx  and OxyPond & Stream Cleaner that we offer that can help without the risk of hurting your fish or plants. Stop by or give us a call for details.

Finally, keep in mind that algae is a people problem- the fish don’t care! After all, how many ponds do you see in Ohio with crystal clear water? We’re just trying to tweak mother nature just a little so we can see all the beautiful residents of our little piece of watery paradise!


Winter Care

Most hardy plants can be trimmed to about 3-6” after November 1st and placed in the deep section of the garden. Aquatic grasses, reeds, cattails, rushes and similar grass-like plants should be only trimmed back to about 18 ” and placed in shallow water so that their stems rise above the surface of the water. These plants “breathe” through their stems in the winter. Water iris should not be moved to deep water since they can suffocate in water more than a few inches above the pot. (Ask for our handout, Seasonal Care of Water Plants for more detailed information about specific varieties.)

There are several options for “winterizing” your fish. As mentioned earlier all feeding of the fish should stop after the water temp falls below 43-50 degrees- usually about late October.

Your fish do require having access to fresh air during long periods of frozen ice in the winter. One way to accomplish this is simply to do nothing!. Just let your waterfall continue to run as it has all season and the moving water will not freeze and provide the needed air exchange. Even in severe cold, ice will form over the moving water, but the flow will not stop. The main concern would be a temporary power outage that might allow water to freeze in the line blocking the water flow even when power resumes. For this reason, if you expect to be away from your pond for extended periods over the winter we would suggest one of the following alternative methods.

A second option is to disconnect the pump from the waterfall (or use a separate pump 1    20 gph or larger) and place it about 6-8” below the water surface with the outlet pointing up so that it creates a bubbling, mini-geyser at the water surface. When plugged in, this moving water helps prevent total freezing of the surface. Even after a power outage, when the pump is turned back on it will quickly melt through any ice that has formed on the surface. Be sure your pump still has a pre-filter attached to the inlet during the winter. If your primary pre-filter can’t be used, most pumps come with a smaller built-in or attachable pre-filter that will usually suffice.

A third (preferred) option is to replace the pump with a floating de-icer during the coldest winter months. Simply set the de-icer in the pond, anchoring it with a stake or stone so that it doesn’t touch any exposed liner. Plug it in, and you’re done! A built-in thermostat will turn it on when water temperature drops below freezing and off when it is not needed. Adding a small aeration stone running with the deicer is even more ideal especially for ponds with heavy fish loads.

To save some electricity, the de-icer need not run all the time if it has an exposed heating element. Simply, store the de-icer in the garage or somewhere else handy and just plug it in after the pond freezes (setting it on top of the ice). The exposed heating elements will melt a hole through the ice cover within 24 hours. The goal is just to prevent more than 10 days or so of uninterrupted ice cover in your pond. A few days to a week of ice cover for a healthy pond is not harmful. However, if your pond is relatively dirty and/or has an extra-large fish load, we recommend maintaining a continuous air hole with your de-icer or pump.

If your pump is not being used over the winter, it can be stored in any ice free area of the pond or in a bucket of water indoors until the spring. Any underwater lights should be moved to an ice-free area also, or they can be pulled out and set along the edge (out of water) of the pond till spring.

If you have tropical plants you can bring them indoors as houseplants over the winter or discard and replace them next spring. Umbrella palms do especially well indoors over winter. Tropical water lilies and floating plants are best replaced each year unless you have access to a greenhouse that stays 65-75 degrees through the winter. Any tropical plants you wish to save be sure to move to a warm location before the first frost. Floating plants killed by frost should be immediately removed so that they do not add to the plant debris in your garden. Tropical plants should not be placed back into the garden in the spring until water temperature reaches 65-70 degrees (usually late May to June 1).

Once the chance of prolonged freezing spells are past (late-March), you can return your pump(s) and underwater lights to their regular locations. Any plants can also be retrieved from deep water winter bed and placed in their regular locations.


Annual Cleaning

Once a year you should give your water garden a good cleaning. Late fall, while you prepare your garden for winter, or early Spring (March/April) are the best times for cleanings. Drain your pond with a pump placed in the deep section of the pond. Place your fish in a separate container of pond water, remove all plants and clean out any debris that has collected at the bottom of your garden. Refill your garden with fresh water and return all plants. Before adding your fish back give them a chance to adjust to any change in water temperature and treat the water to remove any chlorine or other harmful additives.

If your pond is stone-lined, clear a location of gravel in the deepest area of your pond to place your pump. Using a regular garden hose with a jet spray attachment, wash any collected sediment down between the rocks to the low area where your pump can pump it out. Collect and discard any leaves, stems, twigs etc. that may have collected on top of the stone. There should be no need to remove/replace any stone during the cleaning process.

If your pond is relatively clean and the water has been clear most of the season, it is not necessary to completely drain the pond to clean it. Rather, simply drain about 75% of the water(pumping from the bottom as you stir your water up a little to pull out any accumulated debris. Set aside all plants and leaving the fish in the pond, net out any large debris that the pump did not remove, re-filling the pond slowly to allow the fish a chance to adjust to the water temperature. Remember to apply a dechlorinate unless you are using well water.

Your goal in either cleaning procedure is to remove 95% of the accumulated debris/sludge in the pond as quickly as possible without disturbing the fish any more than necessary. There is no need and it is actually detrimental to ‘scrub’ down the pond when you clean it.... you’ll just be killing the beneficial bacteria/algae that lives in the green film covering the liner! So remember, in this case, quick and easy is best!

After a fall cleaning we highly recommend to stretch a leaf net across your pond through the fall and winter to prevent wind blown leaves and debris from collecting in your pond. If no leaf net is used be sure to “skim” your pond with a hand net on a regular basis.

Cleaning can be repeated any time during the year your water becomes excessively “dirty’ with floating debris or waste. We do not recommend summer cleanings except in severe cases since it tends to disrupt the balance of the eco-system which we are trying to maintain. However, with a proper balance of fish & plants with minimal care, a cleaning should not be required more than once a year.



Feel free to give us a call if you have any further questions or concerns. Water gardening is a fascinating, easy hobby once you learn the basics of the new eco-system you have created. Enjoy your new water garden!