Well, this one is short and simple. It’s not a good idea to use a pool pump in your fish pond because they can very easily end up killing your fish.
The main issue with pool pumps is that they’re designed to have a very high flow rate, while fish ponds need a much lower flow rate for the best water quality.
That’s right, too much flow is actually bad for your fish, and for a couple of reasons.
Fish Stress
The first reason is that fish get stressed by too much flow. This is because they’re constantly having to swim against a current, which is obviously pretty tiring.
Now, this isn’t just some minor inconvenience for your fish. It’s actually pretty serious. Fish that are chronically stressed from having to swim against a current all the time can eventually weaken and die.
With a pool pump, there’s no way to slow down the flow of the water to a rate that won’t stress your fish out. With a proper fish pond pump, you can adjust the flow rate to exactly what you need it to be.
Poorly Oxygenated Water
The second reason why too much flow is bad for your fish is that it doesn’t allow the water to stay in contact with the air long enough to pick up enough oxygen from it.
Picking up dissolved oxygen from the air is the main way that fish “breathe” in the oxygen that they need to live. They get some oxygen from their gills, but they get the majority of it from the water around them.
This means that if the water in your pond isn’t getting enough oxygen from the air, then your fish won’t be able to get enough oxygen from the water, and they’ll eventually suffocate.
Having a high flow rate in your fish pond doesn’t just deprive the water of oxygen. It also doesn’t allow enough time for the carbon dioxide in the water to evaporate out of the water.
When there’s too much carbon dioxide in the water, it makes the water acidic. It’s not usually a problem because fish ponds usually have enough plants in them to use up the carbon dioxide and produce oxygen in its place.
However, if the water is always being pumped so quickly that the carbon dioxide doesn’t have time to be used up by the plants, then the water will gradually become more and more acidic.
The pH of water is a logarithmic scale, so the lower the pH, the more acidic the water is. The problem is that fish can’t handle acidic water. They can only tolerate water that’s slightly alkaline.
The thing about having too much flow in your fish pond is that it’s not just the fish that you need to worry about. It’s also your pond life in general.
The fact is, high flow rates are just generally bad for fish and pond life. They’re meant to live in still or slow moving water, after all. If you have a high flow rate in your fish pond, then the first thing to suffer will be your fish, but your pond plants will start to wither and die, and the same goes for your beneficial bacteria that keep your pond clean and healthy.
If you think about it, it’s kind of like how a strong wind can suck the moisture out of plants and dry out the soil. Wind can also damage plants and make them wither and die. That’s why there are windy deserts and windy desolate places like the surface of Mars.
The point is, high flow rates are unnatural and force your pond life to endure harsh conditions that they’re not designed to handle.
If you’re going to have a waterfall in your fish pond, then it’s essential that you use a proper pond pump that’s designed specifically for fish ponds.
The lowest flow rate that you’ll usually be able to get away with is 300 gallons per hour (abbreviated to GPH). Anything higher than that and you’ll start to stress your fish.
