Active Sponge Filter

Filter - Active Sponge Filter

Regular price $10.95
Shipping calculated at checkout.

You should choose a carrier that can get these to you within 2-3 days transit time, Priority Mail is a very unreliable choice when selecting the shipping method. Please do NOT order so it travels over a weekend.

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.  

We cannot tell you how many 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 new-born 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 are 50ppi Charcoal. 

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 try to make sure the carrier you choose will get them from our location (14760) to yours, within 2-3 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.  Orders that arrive after 8 AM est, will not ship until the following business day.

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 be as effective in establishing your aquarium.

We are not fans of "fish-less" cycling. It seems most times a customer is having trouble cycling their aquariums with our filters, it's a "fish-less" cycle. It's possible some additive in the ammonia they're adding, is interfering with their water test kit readings or is simply doing something to the nitrifying bacteria. 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. The 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, 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 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 what happens in biological 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 much 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 is 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, 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 reactivates 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 a bit slower as they 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.

Customer Reviews

Based on 145 reviews
Cant believe I waited so long..

Been attemtping to cycle my tank for 9 weeks with fish in, doing constant WC with about 1ppm ammonia. This filter took less than 24 hours to completely cycle my tank and has been in since. Thanks Angels!

Seems to be working well.

I installed the active filter in a 20 gallon tank and it seems to be accelerating the cycling process. We aren’t there yet but levels seem to be doing what the company said they would. We also have guppies in there, we are prepping the tank for an Axolotl.


We were having so much trouble cycling our 45 gallon tank. After 6 weeks, we were almost there, but it crashed and we had to start all over. After 2 months of nearly constant water changes, trying to get my ammonia lower than 2.0 ppm, I ordered 3 of these filters. One filter for the (nearly) cycled 25 gallon, two filters in the 45 gallon, and within 3 days, the 45 gallon was cycled: 0ppm ammonia, 0ppm nitrites, and 10ppm nitrates. I could tell the difference in my fish, too. They seemed happier and more active; no longer lounging on the bottom of the tank or gulping at the surface.
I would recommend these filters to anyone doing a fish-in cycle. They work!

24 Hours later i had 1.0+PPM of nitrite

Started up a new Hospital/Quarantine tank for new comers or sick fish. I have PLENTY of cycled media but figured i’d give these guys some love and put the “dose it work” comments to rest once and for all on the forums. i’ve used these in the past COUNTLESS times, for friends/family and of course myself! and they work every time!

Put the filters in the water at 530pm wednesday evening. at the time i had very little ammonia, 0 nitrite and 2PPM nitrate which unfortunately is in my tap water. treated with prime and threw 4 feeders inside to help create some waste. woke up tested water, had ammonia, probably from the feeders pooping everywhere overnight, had a faint purple tint(.25ppm at best) to the nitrite API test. 5 ppm of nitrate.

retested at 530pm thursday evening, greater with little ammonia, between the 1-2ppm color of nitrite, and 5 ppm of nitrate. WITHIN 24 HOURS i had nitrite readings.

tested again thursday morning had almost zero ammonia, 2.0ppm nitrite and 5.0ppm nitrate.

at this right my tank will be cycled by the weekend! i’m not sure how it will do once i pull the filters because they are not nice quality at all, decently porous foam, but look horrible. that is my only complaint!

i will edit this if anything changes but for the amount of ONE bottle of aquavitro Seed or Stability, you can get a preseeded filter and be fish ready id guess within a week or so. the fact of the matter is i had nitrite readings in less than 24 hours when that normally takes a week alone.

THANKS angels plus for coming in clutch!

Definitely helped with cycling

Hit a stall in my cycling process and wanted to try to jump start it again. Did the trick! Will admit that I’m still in the cycling process but this filter pushed me forwarded after being stagnant for weeks. In the final phase!