Getting Your Pond Ready for Springtime

Preparing Your Pond for Spring

As temperatures begin to rise and the pond becomes more active again, spring is a good time to inspect your pond, check your equipment and gradually prepare your fish and filtration for the warmer months ahead.

This guide is primarily intended for ornamental ponds containing koi, goldfish and similar pond fish. Wildlife ponds generally need less intervention, so avoid unnecessary cleaning or disturbance where fish and filtration are not involved.

Spring Pond Maintenance Checklist

As the weather begins to warm:

• Remove excessive leaves, dead plant material and winter debris.
• Check the pond, liner and water level for signs of winter damage or leaks.
• Inspect pumps, pipework, fountains and waterfalls.
• Check and service your pond filter where necessary.
• Clean the UV quartz sleeve and check whether the UV lamp is due for replacement.
• Test ammonia, nitrite and pH before significantly increasing fish feeding.
• Reintroduce fish food gradually as the water warms.
• Check pond plants and divide or repot overcrowded plants where necessary.
• Keep an eye on green water and blanket weed as light levels increase.
• Watch your fish carefully as they become more active.

Remove Winter Debris and Check Your Pond

Start by removing excessive fallen leaves, dead stems and other accumulated debris that may have entered the pond over winter. Removing decomposing organic material helps reduce the amount of waste entering the pond as temperatures rise.

Avoid trying to make the pond completely spotless. A complete pond clean-out is rarely necessary and can cause unnecessary disruption, particularly in wildlife ponds.

If removing old plant growth, check it for pond creatures and leave it beside the pond for around 48 hours before composting it, giving smaller wildlife an opportunity to return to the water.

Check the water level and inspect accessible areas of the liner, edging and pipework for signs of damage or leaks. A continuing or unexplained drop in water level may indicate a leak rather than normal evaporation.

Check Your Pond Pump and Water Features

Inspect your pond pump, hoses, connections, fountains and waterfalls before the main pond season begins. Remove any accumulated debris and make sure that water can flow freely.

If equipment has been switched off during winter, check it carefully before restarting it and follow the manufacturer's instructions for your particular pump, filter or water feature.

If your pump and filtration have continued running throughout winter, spring is still a useful time to inspect the system and carry out any routine maintenance recommended by the manufacturer.

Service Your Pond Filter Carefully

Spring filter maintenance depends on the type of filtration system and whether it has continued operating through winter.

Mechanical filter foams may need accumulated debris removing, but biological filter media should not be aggressively cleaned. If biological media needs rinsing, use water removed from the pond rather than untreated tap water, as chlorine or chloramine can damage the beneficial bacteria living on the media.

If your filter has been switched off for an extended period, its biological bacterial population may need time to recover as the pond warms and feeding increases. Increase feeding gradually and monitor water quality rather than assuming the filter can immediately cope with a full summer feeding level.

Proprietary filter-starting bacterial products can also be useful in some situations when used according to the manufacturer's instructions. They should support, rather than replace, gradual feeding, suitable filtration and regular water testing.

Check filter foams for deterioration while carrying out maintenance. If foams have become badly misshapen, unusually soft or are beginning to break down, they may need replacing. Where several pieces of established biological media need replacement, avoid replacing everything at the same time unless the filter manufacturer specifically recommends otherwise.

You can find replacement components in our pond filter and pump spare parts section.

Check Your UV Clarifier Before Green Water Season

Spring is a good time to check the UV clarifier fitted to your pond filtration system.

Check the quartz sleeve at the same time. Limescale, algae and other deposits on the quartz can reduce the amount of UV light reaching the water.

For step-by-step instructions, see our guide to cleaning a pond UV quartz sleeve.

Spring is generally the best time to replace a pond UV lamp that is approaching the end of its recommended service life. This ensures the lamp is producing its strongest effective UV output during spring and early summer, when increasing light levels and temperatures can encourage rapid growth of green-water algae.

UV lamp life varies between manufacturers and lamp types. Some older conventional tube-style lamps may have shorter recommended replacement intervals, while many modern pond UV lamps are designed for approximately 8,000–9,000 hours of effective use, which is roughly one pond season or around 12 months depending on how the unit is operated. Always follow the replacement interval specified by the UV manufacturer.

Remember that a UV lamp can still appear to be glowing after its effective UV output has fallen significantly, so appearance alone is not a reliable indication that the lamp is still performing at full strength.

If your lamp is due for replacement, see our range of replacement pond UV and UVC bulbs.

Test Your Pond Water Before Increasing Fish Feeding

Water quality becomes particularly important in spring because fish activity and feeding can increase faster than the biological filter's ability to process additional waste.

For ponds containing koi, goldfish and similar pond fish, test the water regularly. OATA advises that:

• ammonia should be zero;
• nitrite should be zero;
• pH should be monitored;
• nitrate can also be useful to monitor.

If ammonia or nitrite is detectable, investigate the cause and avoid significantly increasing feeding until water quality is under control.

Common causes include increasing feeding too quickly, accumulated organic waste and biological filtration that has not yet adjusted to the increased waste load.

Our pond water test kits can be used to check the main water-quality parameters.

When Should You Start Feeding Pond Fish in Spring?

Use the pond water temperature and the behaviour of your fish rather than the calendar or daytime air temperature when deciding when to increase feeding.

As the water warms, the metabolism and appetite of koi and goldfish gradually increase. OATA recommends reintroducing food slowly in spring and advises that when pond water is below approximately 8°C, it may be better not to feed koi and goldfish at all.

When feeding resumes, start with small amounts and increase the quantity gradually while monitoring both the fish and water quality. Easily digestible foods such as wheatgerm pond fish foods are commonly used during cooler conditions.

Only offer an amount that the fish will readily eat. Excess food left in the pond adds unnecessary organic waste and increases the load on the biological filter.

Sturgeon are an important exception. They have different nutritional requirements and OATA recommends that sturgeon continue to be fed throughout the year.

For more detailed guidance on temperature, food types and feeding quantities, see our guide to how and when to feed your pond fish.

Prepare Pond Plants for New Growth

Spring is also a good time to tidy pond plants and remove dead growth remaining from the previous year.

Overcrowded marginal plants can be divided, and established waterlilies can be divided or repotted once they begin showing new growth. Avoid removing more vegetation than necessary, particularly in wildlife-friendly areas of the pond.

When removing old vegetation, check it for pond creatures and leave it beside the pond for around 48 hours before composting it.

Why Does Pond Water Sometimes Turn Green in Spring?

An increase in algae is common during spring as increasing light levels and rising temperatures encourage growth while pond plants are only beginning their new season's growth.

Do not assume that a short period of green water means the entire pond needs cleaning or treating.

If green water persists, check the UV clarifier, filtration, water quality, fish stocking and feeding levels. Suitable pond planting can also help provide shade and compete for nutrients.

For more detailed troubleshooting, see our guide to clearing green pond water.

Keep an Eye on Your Fish in Spring

Observe your fish as they become more active after winter. Healthy fish should gradually become more interested in food and resume normal swimming behaviour as temperatures rise.

Pay particular attention to unusual behaviour, damaged skin or fins, abnormal breathing, persistent isolation or loss of appetite.

If something appears wrong, test the pond water first. Poor water quality can cause symptoms that resemble disease, and ammonia or nitrite should not be detectable in a healthy established fish pond.

If the water tests are satisfactory but your fish still appear unwell, see our pond fish symptoms and treatment selection guide before choosing a treatment.

Frequently Asked Questions About Spring Pond Care

Should I completely clean my pond in spring?

Usually not. Remove excessive debris and carry out necessary maintenance, but avoid completely stripping down a healthy pond without good reason. Excessive cleaning can disturb its biological balance and wildlife.

Should I restart my pond filter in spring?

If your filter has been switched off for winter, restart it in accordance with the manufacturer's instructions as conditions begin to warm. Remember that the biological filter may need time to regain capacity, so increase fish feeding gradually and monitor ammonia and nitrite.

Should I replace my UV lamp every spring?

Not necessarily. Spring is a convenient time to check it, but replacement intervals vary according to the UV lamp and manufacturer. Follow the recommendations for your particular unit.

Can I feed pond fish when the water reaches 6°C?

There is no need to use 6°C as a universal starting temperature. OATA advises that below approximately 8°C it may be better not to feed koi and goldfish at all and recommends reintroducing feeding gradually as temperatures rise. Consider the water temperature, fish behaviour and water quality together.

Do I need to add filter bacteria in spring?

Not every pond needs additional bacteria. Proprietary bacterial cultures can help support and encourage filter maturation or recovery when used according to the manufacturer's instructions, but they are not a substitute for good filtration, gradual feeding and regular water testing.

Continue Your Seasonal Pond Care

Once spring and summer are over, preparing the pond properly for colder weather can help reduce problems during winter. See our Autumn Koi and Goldfish Pond Maintenance guide for advice on feeding, fallen leaves, sludge, water quality and preparing equipment for colder conditions.

Need More Help Getting Your Pond Ready for Spring?

If you are unsure about restarting your filtration, feeding your fish, replacing a UV lamp, checking water quality or preparing your pond equipment for spring, our experienced team is happy to help.

You can ask our pond experts a question online, or call us on 01778 341199 for friendly, practical advice.

Sources and Further Reading

• Royal Horticultural Society (RHS) – March pond care
• Royal Horticultural Society (RHS) – Pond care
• Ornamental Aquatic Trade Association (OATA) – How to look after pond fish
• Ornamental Aquatic Trade Association (OATA) – How to set up and look after a garden pond

Last reviewed: September 2026