Winter in Central Iowa is hard on a lot of things — and your backyard pond is no exception. But the good news is that spring is when ponds truly come alive. Ice melts, pumps restart, water begins moving again, and your outdoor retreat starts its transformation from a dormant, frozen feature into a dynamic, thriving ecosystem.

This guide walks you through exactly what's happening to your pond and its equipment as temperatures rise — month by month, from the first thaws of March through the warmth of May — and what you should be watching for to make sure your water feature has the best possible start to the season.

Central Iowa winters are no joke. Temperatures routinely drop into the single digits, and the freeze-thaw cycles of late fall and early spring are especially punishing on water features and their mechanical components. Understanding what's been happening below the surface helps you know what to look for when things warm up.

A properly winterized pond with a de-icer and aerator will maintain an open hole in the ice, allowing gas exchange. But even well-maintained ponds accumulate debris over winter — decomposing leaves, organic sludge, and suspended waste settle to the bottom. This material will begin breaking down rapidly once water temperatures climb, creating the murky green or brown water many pond owners see every spring.

The pond liner and rocks also experience stress from freeze-thaw cycles. Ice expanding and contracting can shift boulders, dislodge edging stones, and — in some rare cases — create small stress cracks in liner material near the water's edge.

Most pond owners turn their pump off in late fall once water temperatures drop below 50°F. This protects the pump from ice damage and prevents cold water from recirculating through the biological filter before it's ready to function. After months of sitting dormant, the entire mechanical system needs to be evaluated before spring startup:

The most common spring complaint from pond owners. String algae (also called filamentous algae or blanket weed) looks like long green threads or mats attached to rocks and the pond floor. It's completely normal in early spring because it thrives in cool water and activates before the beneficial bacteria in your biofilter do. As water warms and your biological filter re-establishes, string algae pressure typically eases on its own — but it can get out of hand if the pond isn't properly cleaned in spring.

A thorough spring cleanout dramatically reduces string algae by removing the excess nutrients — accumulated sludge, organic waste, and debris — that fuel its growth.

Green water is caused by microscopic suspended algae (not the same as string algae) and is most common in the 4–6 weeks after startup while your biofilter builds back up. A functioning UV clarifier is your best tool here — it kills suspended algae as water passes through it. If green water persists past mid-May, it's worth having the UV bulb checked and the overall nutrient load of the pond assessed.

Spring is when liner leaks often become apparent. During winter, the pond may have been lower due to the pump being off, and any leak hidden by normal water level fluctuations becomes visible once the system is running. If you're losing more than 1–2 inches of water per week (accounting for evaporation), it's worth having the pond inspected for a liner issue or plumbing leak.

The most common leak locations: the waterfall spillway, stream edges where rocks may have shifted, and plumbing connections at the pump or BioFalls.

A pump that struggled at shutdown last fall will often fail to start in spring. Before assuming the pump is dead, check for debris in the impeller housing and make sure the intake isn't blocked. Reduced flow that doesn't improve after cleaning the impeller usually indicates a worn motor or failing impeller, and pump replacement is typically the most cost-effective path. Most quality pond pumps have a 3–5 year lifespan depending on conditions and maintenance.

Freeze-thaw cycles are hard on rock work. Every spring, it's worth walking the edge of your pond and waterfall to check that boulders are still firmly seated and that the waterfall coping stones haven't shifted. A slightly shifted stone on the waterfall spillway can redirect water off the liner and cause significant water loss that looks like a leak.

Many pond owners tackle their own spring startup with good results — but a professional spring cleanout goes further than most DIY efforts and sets the pond up for the entire season.

The difference shows up most clearly by midsummer. Ponds that had a thorough spring cleanout typically have better water clarity, less ongoing algae pressure, and fewer mid-season filter problems. The accumulated sludge and organic waste that a drain-and-clean removes is the primary fuel for algae growth all season long.

Just Add Water serves Central Iowa pond owners in Des Moines, Ankeny, Johnston, Indianola, Ames, and surrounding communities. As Central Iowa's only Master Certified Aquascape Contractor — and the 2023 Aquascape Contractor of the Year — we've opened hundreds of ponds across the region every spring.

Our spring cleanout appointments typically begin in April and fill up quickly. Pond owners on our maintenance program are scheduled first, followed by our regular customer list. If you're not already on a maintenance program, spring is a great time to get connected — one cleanout appointment is often the start of a relationship that keeps your pond performing season after season.