We get phone calls every spring that all start the same way: “I don’t know what happened. Everything seemed fine, and now…”
Low water levels. Sluggish fish. Ponds that look a little … off. And one very concerned pond owner on the other end of the line who definitely did not mean to cause any harm.
The good news: most of these situations are completely preventable. The not-so-good news: a lot of common “helping” behaviors are exactly what gets Iowa pond owners in trouble every spring. If you’ve got koi and a pond, this list is for you.
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1 Topping Off Your Pond with a Garden Hose — Without Thinking About the Temperature
It’s a warm spring afternoon, you notice your water level is down a few inches, and you grab the hose. Seems harmless, right?
Here’s the problem: that hose water sitting in a line or coming out of a municipal system can be significantly colder (or warmer) than your pond water. Koi are cold-blooded creatures whose entire immune system and metabolism are tied to water temperature. A rapid shift, even just a few degrees too fast, creates serious stress that can make them vulnerable to illness.
The FixTop off slowly, never all at once. If you’re adding more than a small amount of water, do it gradually over time and let the temperatures equalize. When in doubt, less is more. Keep the hose out of the water — this keeps fish from swimming in the new current and acts as a reminder that the hose is running.
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2 Adding Tap Water Without a Dechlorinator
This one catches a lot of people off guard. Municipal tap water is treated with chlorine and chloramine to make it safe for humans to drink, but those same chemicals can be toxic to your pond’s ecosystem and hard on your fish.
Every time you top off or do a partial water change without neutralizing the water first, you’re introducing chemicals directly into an environment where living creatures depend on water quality to survive.
The FixKeep a quality dechlorinator/water conditioner on hand at all times and add it whenever you’re introducing fresh tap water to your pond. It takes about 30 seconds and makes a big difference.
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3 Letting Water Levels Drop Too Low in the First Place
Spring evaporation catches people off guard, especially after a dry stretch or a stretch of warm, windy days. A pond that loses several inches of water over a short period isn’t just a visual problem. Lower water volume means less dilution of waste, faster temperature swings, and less room for your fish to move comfortably.
This is probably the most common call we get: “My water is low, what do I do?” The answer isn’t to dump in a bunch of water all at once — that circles back to Tip #1. It’s to top off consistently in smaller amounts so levels stay stable.
The FixMake a habit of checking your water level weekly during spring and summer. Small, consistent top-offs are much safer than playing catch-up with a big refill.
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4 Overfeeding — Because They Look Hungry (They’re Not)
Koi have a way of swimming toward you with those big, hopeful eyes and convincing you they haven’t eaten in weeks. Don’t fall for it.
In early spring, your pond water is still warming up and your fish’s metabolism hasn’t fully kicked in yet. Any food they don’t consume within a few minutes sinks to the bottom and starts breaking down. That decomposing food releases ammonia into the water — and elevated ammonia is one of the fastest ways to stress or harm koi.
The FixFeed only what your fish can eat in about five minutes, once a day. When water temps are below 50°F, skip feeding altogether. If you see uneaten food floating around after five minutes, you’re overfeeding.
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5 Scrubbing Your Pond “Clean” in the Spring
We totally understand the impulse. Spring rolls around, you look at your pond, and it looks… murky. Gross, even. You want to drain it, scrub every rock, power-wash everything back to looking brand new.
Here’s the thing: that biological gunk coating your rocks and filter media? It’s not dirt. It’s your pond’s beneficial bacteria — the living filtration system that processes fish waste and keeps your water chemistry balanced. Scrub it all away and you’ve essentially reset your pond to day one, which leaves your fish in an unstable environment while the biology rebuilds itself from scratch.
The FixSpring cleanouts should be thorough but careful — not sterile. Remove debris, rinse (don’t scrub) filter media with pond water (not tap water), and leave the biological layer intact. This is exactly the type of work our spring maintenance visits are designed to handle correctly.
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6 Using Lawn or Garden Chemicals Near the Pond
Spring yard work goes hand-in-hand with pond season, and that’s exactly where things can go sideways. Herbicides, fertilizers, weed-and-feed products, and pesticides applied anywhere near your pond can make their way into the water through overspray, runoff after rain, or just drift on a breezy day.
These chemicals are formulated to kill things. They’re very good at their job. Your pond is not on their approved list, but the water doesn’t know that.
The FixCreate a buffer zone around your pond — no chemical applications within at least 10 feet. When in doubt, go organic in that area or skip treatments altogether. If you hire a lawn care service, make sure they know about your pond.
You Don’t Have to Figure This Out Alone
The calls we get every spring aren’t from careless pond owners — they’re from people who genuinely love their ponds and just didn’t know what they didn’t know. That’s completely understandable. Pond ecosystems are surprisingly complex, and it’s easy to do the wrong thing while trying to do the right thing.
That’s exactly why we offer spring maintenance visits and ongoing pond care programs. We handle the cleanout correctly, check your water quality, inspect your equipment, and make sure your pond — and everything in it — is set up to thrive through the season.
If your pond is already in a good spot, great — now you know what to watch for. If you’re already seeing some of these warning signs, give us a call. We’re happy to help before a small issue turns into a bigger one.
(515) 208-4099 — Call Us Today Central Iowa’s only Master Certified Aquascape Contractor — we’d much rather help you prevent a problem than respond to one.