We are reader supported. When you purchase through links on our site, we may earn an affiliate commission. Also, as an Amazon affiliate, we earn from qualifying purchases.
Setting up a fresh new aquarium is one of the best parts about the fish-keeping hobby. Picking out the perfect plants, substrates, decorations, and livestock is both exciting and rewarding, and watching your fish take to their new home is an experience like no other.
But a short time after setting up an aquarium, many tank keepers notice a brown, slimy film beginning to cover their decorations, pants, and even the tank glass. This algae, known as diatoms, is a common occurrence that is the bane of many aquarium fans.
The appearance of a lot of diatoms in a new tank is known as a diatom bloom. So, how long does a diatom bloom last?
Diatom blooms will usually resolve themselves within 3-6 weeks. They appear because of an imbalance in nutrients in tank water, but once the nitrogen cycle is established, the diatoms will starve and disappear.
A diatom bloom can be frustrating, but the appearance of one can indicate that your tank isn’t cycled, and while diatoms aren’t dangerous to tank livestock, an uncycled aquarium is.
In this article, we will discuss how long it takes unsightly diatoms to resolve and if there are any quick fixes.
How Long Does A Diatom Bloom Last?
Something that is always frustrating to hear is that there is no way to actually resolve a problem. Unfortunately, this is the case with a diatom bloom. The only real solution to a diatom problem is patience.
A diatom bloom will last between 3 and 6 weeks, or however long it takes an aquarium to cycle. Cycling refers to an aquarium establishing its own nitrogen cycle.
Waiting almost 2 months for the ugly, brown diatom algae to go away can seem like torture, especially to tank keepers that take pride in their fish tanks appearance, but ultimately, time is the best treatment of them all.
Products in stores may claim to fix a diatom bloom quickly, but adding chemicals or even algae-eating livestock to a tank can do more harm than good. A diatom bloom is usually only present in an uncycled tank, and the addition of chemicals can cause a tank to go back to square one with cycling.
Adding shrimp or snails to clear the diatom algae may seem like a great idea, but a tank without a nitrogen cycle is a harmful environment, even to invertebrates. So instead of trying to fix your diatom bloom, your best option is to just wait it out.
What Are Diatoms?
Diatoms are a type of plankton, called phytoplankton. Diatoms are single celled microorganisms, and are present in both fresh and saltwater.
Diatoms require silica to grow, namely silicon dioxide, because their box-like cell walls are made of this chemical.
Some types of algae have their place in aquascaping, but not diatoms. During a diatom bloom, the diatoms form a brown, slimy layer on any available surface, making a previously clean tank appear sloppy and unkempt.
Diatom algae usually disappears once a tank is cycled.
Will A Diatom Bloom Go Away?
Yes, once your aquarium is cycled, the diatom bloom will go away. Once a nitrogen cycle is established, the diatoms will have nothing to feed on, subsequently starving to death and disappearing.
That being said, there are circumstances where diatoms may stick around long past their welcome. If a tank is stuck and unable to cycle, the diatoms won’t go away. They only disappear once they are out-competed for food by the bacteria present in a completed nitrogen cycle.
Diatoms can also show up if a cycle crashes, or even comes close to crashing. Once the crash has resolved, the diatoms will once again depart.
How Do You Fix Diatom Blooms?
The only way to fix a diatom bloom is by waiting it out, and cleaning the diatom algae from the tank surfaces as it appears.
If a diatom bloom is particularly prevalent, it may persist longer than usual. In cases like this, or if you just want to get rid of some of the unsightly algae, you can clean it from your tank.
The most popular method of removing diatoms is to siphon them off with an aquarium vacuum. Another successful way of removing diatoms is just to clean it off with a cleaning brush or scrub pad.
Do Diatoms Mean My Tank Is Cycled?
No, diatoms don’t indicate that a tank is cycled. What they do indicate is that the tank is in the process of cycling.
Diatoms appear in cycling tanks at around the 3 week point. Cycling a tank is a lengthy process, but the appearance of diatoms won’t hinder this long process. If having them around is particularly bothersome, feel free to clean them off with no repercussions.
What eats diatoms?
Snails, particularly the Nerite variety, will eat diatoms. That being said, they’ll eat other food first if available. It’s also unwise to add any livestock to an uncycled tank.
Do diatoms disappear at night?
Like other plant life, diatoms are dependent on the light. Once the lights go out, they will seem to disappear, but in reality, they are just becoming less prevalent until more light is available.
Do diatom blooms happen after a water change?
Diatoms don’t usually appear after a normal water change, but if the water change is large enough to disrupt the nitrogen cycle, a small diatom bloom can occur. Once the nitrogen cycle is reestablished, the bloom will disappear.