Active Sponge Filter

Filter - Active Sponge Filter

Regular price $13.95
Shipping calculated at checkout.

Please read before ordering!

Orders with Active Filters that are placed after 8 AM est, will not ship until the following business day. You should choose a carrier that can get these to you within 3 days transit time, UPS Ground is not a guaranteed time-in-transit service. Priority Mail is an unreliable choice when selecting the shipping method. The post office is late more often than not. Please do NOT order so it travels over a weekend. UPS does NOT deliver on weekends. 

NOTE: If you test your water after adding the filter and have no ammonia and no nitrites, then everything is good. You do NOT need to see nitrates to know it's working. 

If you use Prime or another ammonia-neutralizing product, the filter will not work well. These products interfere with the nitrogen cycle and are not good for biofilters of any kind. It will delay the cycling of your tank and may even kill the filter. If you have chlorine, use a simple dechlorinator. If you use bottled ammonia, instead of live fish to provide the ammonia the filter needs, the filter's nitrifying bacteria may die. Too much ammonia can kill the nitrifying bacteria. Bio-filters require ammonia to survive, but too much ammonia all at once can kill them and once again greatly delay the cycling of the tank. Many people who add ammonia from a bottle have problems. 

Made from our Pro-Level Reticulated Foam, specifically suited for colonizing nitrifying bacteria at the highest levels in aquariums.

Size: Actual filter size varies with each filter.

  • Large - range from about 50-100 cu/in.
  • Small - ranges from about 30-60 cu/in.  

PPI stands for Pores Per Inch. 30 pores per inch are larger pores than 50 pores per inch.

We cannot tell you how many filters you need for your tank. Tank size does not determine how much filtration you need. Bio-load is the determining factor and it's a complex formula. In general, you have to use your experience to know how much filter material volume your situation needs. If you are inexperienced and must guess, then go with 1 filter per 20 gallons, knowing that it may be over or under-filtered. If you are going to use the active filter solely to establish an existing filter, then one or two max, would be enough for almost any size tank.

If you are putting the filter in with newborn fry or a tank that is 5 gallons or less, then the 50ppi (pores per inch) is the best choice, otherwise, the 15/30ppi filters are a better deal for a much larger size. The Large can be either 15ppi Blue or 30ppi Black - our choice. We send what is ready. The Small is 50ppi Charcoal.  If you want to reduce the chance of finding a small snail in the filter, choose the Small active. The pores are too small for the baby snails to get into.  

It comes with a lift tube. You must supply the airline.

We ship when you order, so it's your responsibility to avoid weekend and holiday delays. You should choose a carrier you think will get them from our location (14760) to yours, within 3 days. They will survive longer, but it will also take longer for the bacteria to build back up to the levels needed for your tank.  

When you receive these, make sure to add any water in the bag to the tank. Do not worry about it being dirty. It is full of nitrifying bacteria and you do not want to throw this out or siphon it out with a water change until the aquarium is fully established.

Filter Setup

When receiving the filter: Be sure to add the dirty water in the bag to the tank with the filter. It contains valuable nitrifying bacteria. 

Setting Up Filter: Run an airline to the lift tube. Insert the airline into the hole in the top side of the lift tube and thread it to within 1/2" of the bottom. Then insert the bottom of the lift tube into the hole in the sponge. You can put the filter into any part of the aquarium. If it floats, gently squeeze the air out of it.

Some people cut these to fit inside of power filters. That will work if the fit is tight, but if water can travel around the filter instead of through it, then that is what the water will do and it will not work as fast in establishing your aquarium.

We are not fans of "fish-less" cycling. It seems most times when a customer is having trouble cycling their aquariums with our filters, it's a "fish-less" cycle. Nitrifying bacteria require a specific range of ammonia and it has to be pure ammonia. Fish provide this best. If you use ammonia from a bottle it has to be the right kind and the concentration must be less than 0.005%. Many people will not get this right. Either way, if you add one of our active biofilters, your tank is ready for fish. Forget about adding ammonia first. Also, do not use ammonia removers when conditioning the water - only chlorine removers should be used if you have chlorine. Ammonia is essential for the bacteria in the filter to survive and grow. If the ammonia gets dangerously high (fish are struggling at the surface), then a water change is the best option.

Occasionally someone complains that their nitrates didn't go down after using this filter. It's important to know that only ammonia and nitrites are lowered by biological filters. Nitrate will actually go up over time, which is why water changes are still necessary no matter how good the filtration is.  

How They Work

These filters are fully "cycled", containing all the many species of nitrifying bacteria a fully established aquarium needs. Once put into a tank, the tank becomes instantly cycled. "Cycled" aquariums can still get ammonia or nitrite readings from a test kit. Cycled means you have the proper number of nitrifying bacteria species and the proper proportion of them. However, the population may not be high enough to handle all the waste produced by your animals. Assuming you have enough filtration for your bio-load, and the water conditions are good for bacteria growth, the bacteria will double in population approximately every 24 hrs in until it reaches the level where it can handle the waste in your tank. That can take anywhere from minutes to days, depending on the bio-load in your tank. Do not use ammonia neutralizers, only chlorine removers unless you have chloramines.  It's best to not do water changes for the first week unless you see the fish struggling at the surface for oxygen. If you must do a water change, we recommend this to remove chlorine.

All of our tanks contain snails, so these filter may have small snails and/or their eggs on them. The filters also have other small micro-life typically found in many aquariums.  There are paramecium and rotifers, There might even be flatworms or bristleworms. These are NOT parasites, but small aquatic animals that clean up extra food and fish waste. We never see them in our tanks and we look for signs of them often. We don't overfeed and they are most visible in tanks that are overfed.  If you don't like them, they are easily killed with formalin.  Just treat in a 5-gal bucket for a couple of hours and then add the filter to the tank. The filters also contain the decomposed waste generated by the plants and animals in our tanks. They will be "dirty". This is not harmful and is normal for all filters. The nitrifying bacteria are short-lived and create a large amount of bio-floc as it dies off.  All of this is normal, but if you are offended by this, please do not order. Filters that are too clean, can be a reason for having a difficult time establishing a bio-filter since cleaning a filter too thoroughly, harms the bacteria.

There are likely hundreds of species of nitrifying bacteria in a tank that has been "established" for over a year. This is why those commercial "starter" products with a few species, don't work very well.  Our filters contain all the species in balance and are why they work so much better.

The bacteria survive shipping quite well, but faster is better when deciding on the shipping method during checkout.  If the filter freezes solid, the bacteria may be killed so pay attention to the weather, here and where you are.  Try to avoid having the package sitting outside after delivery.  It can be risky to order when night-time temps are much below 0 F. We are in a potentially very cold area of the country (zip 14760).  Heat does not bother the bacteria.  In transit, the bacteria go into a dormant state and reactivate in the presence of ammonia and nitrites.  A percentage of them will survive for quite a long time out of an aquarium, so even with delays and bad weather, they persist and will often still work, though they will take longer to recover.

The filters vary in size and shape within the range listed.  All of our Active filters are the "Internal Weight" filter version.  We have too many filter types to have them all in an "active" version and this type is easy to ship without water leaking from the bag.

These filters are "established" in our disease-free aquariums.  This assures that no pathogens are transferred to your fish.  This is safer than using a filter out of your own tanks, since few, if any are disease-free.  These filters have been running for about a month in our super-healthy tanks to ensure the nitrifying bacteria are well-established within the sponge.

On the fence about this Filter - Active Sponge Filter? Don't be. Rest assured that your satisfaction is our first goal.

Inventory Last Updated: Jul 13, 2024

Customer Reviews

Based on 355 reviews
Rebecca Schmidt-Jeffris
Just what I needed

I saw so many excellent reviews I couldn't resist trying this in my new tank. Got the tank cycled in under two weeks and almost a week of that was without the filter! You can go fishless and do ammonia dosing, just don't follow the directions on the bottle and add a set amount: you'll use too much. Just dose until you get the ammonia reading you want from a good kit. I did 1 ppm.

No snails have emerged and no signs of other pests.

I placed an order USPS priority to ship on Monday and it arrived in 4 days, perfectly matching the estimate. I'm on the west coast too.

Great product. I'm surprised more companies don't do this. Would recommend to anyone without access to an old filter to seed a tank with.

Christine Pinkal
Just what was needed!

This was just what I needed. After struggling for 12 weeks to get tanks cycled, broke down and purchased these filters. It cycled the tanks within 12hrs and haven't had a single hiccup since. Customer service was amazing answering my questions and having patience with my indecision. They also went above and beyond to fulfill my requests for seperate packaging (split custody). 10/10 will buy again.

Christopher Junkin
Awesome and inexpensive! ❤ Love it! 🐟 🐠

I bought four of the larger size to go into 10 gallon tanks. I was in a situation where I needed some cycled filters for tanks that were not ready. They came in two days with the correct chosen shipping. Each tank got five ramshorns snails ant two pairs of blue gularis each. It has been 14 days and I have tested water daily. Never saw any ammonia or nitrites and my nitrates started rising day one. Saved me a lot of time and effort.

On top of everything, with shipping it was still cheaper than buying a small sponge filter from Petsmart! Amazing product and service!


Arrived quickly and boosted my almost cycled tank overnight! Thank you!

Mitchell Pereira
This will cycle your tank

I needed this to cycle my tank and that’s exactly what it did. 100% recommend for new tanks