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Getting the filter flow rate correct in an aquarium/fish tank is important for the health and happiness of the tank’s inhabitants. It also helps to keep tank maintenance levels down too.
As a general guide your filter should be capable of filtering all of the water in your tank approximately 4 times an hour. Whether you’ll need less, or more filtration, will depend on your tank setup and the needs of your tank inhabitants. However, most aquariums/fish tanks benefit from having a filter of some kind.
Let’s take a look at what filters do. And why you may, or may not, need one.
Keep reading for some useful information and tips about filter speed for your aquarium/tank
Is A Filter Good For A Fish Tank?
Having a filter in your fish tank is a good thing. Tank filters provide several benefits that help to keep your tank clean and healthy.
Here’s a short list of what a filter does for the water quality in your tank
- Removes floating debris, such as fish poop and other floating particles
- Helps to reduce toxin build-up, e.g. ammonia, nitrate and nitrite
- Oxygenates the water
- Creates flow/current in the water
- Provides a place for beneficial bacteria to grow
- Helps to keep the tank looking clean in between tank maintenance sessions
Do Fish Like Water Flow?
Fish generally like some water flow in their tank. There are very few fish in the fish keeping hobby that don’t need any flow at all. How much flow they need will depend on the type of fish you’re keeping. So you’ll need to check out what speed of flow you need for your fish before buying a filter. Remember that filters don’t just help to clean the water they create movement in the water column. Which means it’s best to get the combination of filtration and flow correct from the start.
And if you’re keeping a community aquarium you need to take the needs of any tankmates in to consideration too.
If you have a community tank with fish, shrimp and snails all living together, you’ll have to keep everyone happy.
It might sound complicated but it doesn’t have to be. Just choose tank inhabitants that like roughly the same tank conditions and things will get a whole lot easier for you to deal with.
How Will I Know If My Filter Is Too Strong Or Too Weak?
You’ll know if your filter is too strong or to weak by observing your fish’s behaviour. If your fish are struggling against the flow/current and hide a lot in sheltered areas it indicates that the flow is to strong. If the filter flow is too weak your fish may become lethargic and not swim/behave in a way that you were expecting them to.
Getting the flow correct can be a bit of trial and error in the beginning. But by watching your fish regularly you’ll soon pick up on any problems.
Read the next 2 sections below for some tips on how to change the water flow in your tank
How To Increase Flow/Current Without Increasing Filtration
You can increase the water flow/current in your tank without increasing the filtration using a few simple methods. So if you’re happy with the level of filtration, but need a bit more water movement, here’s a couple of ideas for you.
- Air Stone – An air stone (Amazon link) run by an air pump through airline tubing (Amazon link) is the simplest way to increase water flow/current in a fish tank. Air stones increase water movement by releasing bubbles that pop at the water’s surface. The bubbles move the water around on their way up and move it even more as the bubbles break the surface of the water. The bubbles make an attractive feature too. You can buy adjustable air pumps (Amazon link) that will help you to get the flow right to suit your fish and their tankmates.
- Wave Maker/Powerhead – Wave makers/powerheads (Amazon link) increase the flow/current in a tank by simply forcing the water around the aquarium at speed. While they don’t increase filtration they agitate the water movement speeding things up in the water column. You can buy adjustable ones if you need/want to control the speed of the flow.
How To Slow Filter Flow Without Decreasing Filtration
If you’re happy with the amount of filtration in your tank but you want to reduce the water flow/current to suit your fish there are some easy solutions.
Here’s a couple of ideas
- Adjustable Filter – You can buy an adjustable aquarium filter (Amazon link) that allows you to control filtration and output flow. These help you to get the balance right for your tank. But if it’s only the output flow you need to slow down take a look at the point below.
- Output Guard/Damper – You can attach an output guard/damper to the return part of your filter that directs the water to the water’s surface. This helps to keep the fastest flow higher in the water column making the lower areas less turbulent. You can make your own or check what’s available to buy. There are lots of ways to slow the flow including using a spout, spray bar or filter sponge.
Take a look at the YouTube video link below. The video is by Girl Talks Fish (A Gamer’s Wife) and she’s got some great ideas for slowing down the flow from your water output.
Should An Aquarium Filter Be On All The Time?
An aquarium/tank filter should run 24/7. It should only be turned off during tank maintenance to stop it from burning out when you’re cleaning the tank. I know that filters stop working during a power outage/power cut but as long as the power isn’t off for too many hours things are usually ok. Some filters need a little help restarting after the power has been switched off. So it’s worth checking that yours has got going again once the power has come back on.
Can You Over-Filter A Fish Tank?
It would be extremely difficult to over-filter a fish tank. In fact it’s probably impossible to do. However, fish tanks and other types of aquariums only need a filter that does the job efficiently with minimal effort. The problem with an extra strong filter is that it often creates a fast flow. Not all fish need a fast flow in their tank. So it’s important to check that both the rate of filter flow and filtration are suitable for your fish.
Do You Need A Filter For A Fish Tank?
Not all aquariums need a filter. But that does depend on the tank setup and the tank inhabitants. Filterless tanks usually contain a lot of live plants that naturally filter the water. The plants use the nutrients produced from the fish etc to grow. This helps to reduce toxins in the water column. The plants also use their root systems to break down and use up the poop that falls into the substrate. Filterless tanks are also generally lightly stocked.
If you don’t have a filter in your tank you will probably need to do more water changes. This helps to keep the water quality up to standard.
Filterless tanks are popular in the fish keeping hobby. Particularly with some fish keepers that have Nano fish, shrimp and/or snail tanks. But you do need to understand the process of building up a no-filter tank before you set one up. So it’s best to do some research before you start.
