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Seachem Purigen is a synthetic absorbent that captures organic waste in the water column. It can absorb and trap nitrogenous organic wastes that would otherwise release ammonia, nitrite, and nitrate. Tannins from driftwood and other natural decor in the aquarium are also captured. Eventually, Purigen will turn dark brown to black, as shown in the photos below. But you don't have to discard it and buy more at this point, because Purigen can be regenerated and reused!

Used Purigen Bags
Used Purigen Bags

The Purigen packet on the left in the above photo was used for just a few weeks in an aquarium with some large pieces of driftwood. The brown color is due to it absorbing tannins from the wood in the water. The packet on the right was used in a different aquarium for several months.

Recharging Seachem Purigen

Basic directions for re-charging Purigen are available on Seachem's website. A screenshot of their instructions is included below:

Seachem Purigen Regeneration Instructions
Seachem Purigen Regeneration Instructions

Bleaching Purigen

I recharged two 100 ml bags of purigen using a solution of 2 cups Clorox bleach and 2 cups water in a plastic container. The bleach burns off organic material that has been captured by the Purigen. You can see the brown and green coloration was completely removed from these two bags after 24 hours.

Bleached Purigen Bags
Bleached Purigen Bags

Dechlorinating Purigen

After soaking for 24 hours in the bleach solution, I mix a solution of 2 cups tap water and 1 TSP of Seachem Safe. Safe is the same thing as Prime, but it comes in a dry powder form and 250 grams treats up to 60,000 gallons. Compare that to a 500ml bottle of Prime, which treats only 5,000 gallons. Per Seachem's instructions, you can use any equivalent dechlorinator, just be sure to use a large enough dose to remove all chlorine.

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This is the first time the packets shown have been regenerated. After multiple uses, Purigen will begin to show staining or discoloration. I don't recommend re-using it more than 3 or 4 times.

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Adult Yellow Tiger Endler Males
Adult Yellow Tiger Endler Males

I recently purchased a few pairs of adult yellow tiger Endler's livebearers. The photo above is a couple of the males in my planted 10 gallon display tank. The best thing about livebearers is how easy they are to breed once you have a pair of adults with good genetics. I set up a simple fry rearing tank, added a very pregnant female, and within 24 hours of moving her I had 15+ newborn Endler fry.

Female Endler After Giving Birth
Adult Female Endler

Tank Setup

Fry Tank Setup
Fry Tank Setup

This setup is optimal for rearing young fish, whether they are livebearers or egg-layers. It requires no substrate and no decorations. All you need is a heater, a filter, and some moss or other plants for the fry to hide in. I am using a 20 gallon "long" size tank, which is shorter vertically and longer horizontally than a typical 20 gallon "high". The light is a 30" Nicrew LED, although a light is not required for raising fry.

1 Day Old Endlers in Java Moss
1 Day Old Endlers in Java Moss

These baby Endlers will be fully grown and ready to breed in about 3 months.

Filtration

Bacto-Surge Sponge Filter
Bacto-Surge Sponge Filter

I'm using a Bacto-Surge sponge filter in this fry tank. A sponge filter is by far the best type to use in a tank with very young fish. Hang-on-back and canister filters have intakes that will suck up and kill newborn fry. Although you can use intake sponges on these types of filters, its much simpler to use an air-driven sponge filter. A 5 watt air pump can drive multiple sponge filters, filtering more than one tank with less electricity than a single hang-on-back.

Bare Bottom

Although you could put gravel into a tank you are using to raise fry, it is much better to run a bare bottom tank. I painted the back and bottom of this tank using black acrylic paint. The bare bottom allows you to easily vacuum out uneaten food and waste to maintain high water quality for the young fish. Having no substrate also saves you about $20 in a 20 gallon tank like this one.

Plants

Plants, such as guppy grass or java moss, provide the fry (or eggs) with a place to hide from their parents, who will often eat their own young. Additionally, plants provide fry with a high surface area to graze on infusoria, which are minute aquatic creatures such as ciliateseuglenoidsprotozoa, and unicellular algae.

Java Moss
Java Moss

I pulled a large quantity of java moss out of another tank that I was rescaping specifically for this setup. You can see several 1 day old Endler fry hanging out beneath the moss in the photo below. If you don't have access to such a large quantity of java moss, guppy grass, also known as najas grass, is often available at local fish shops.

1 Day Old Endlers in Java Moss
1 Day Old Endlers in Java Moss

Feeding The Fry

I feed newly hatched brine shrimp to all of my young fish. Brine shrimp are cheap to produce and can be hatched from eggs in 36 hours. They are small enough for newborn Endlers and Guppies to eat, high in protein, and irresistible to most fish. Fry that are raised on live brine shrimp will quickly outgrow fish that are fed only crushed flakes or other prepared foods. The photo below shows a culture of brine shrimp ready to be harvested.

This post has more information on hatching brine shrimp.

Live Baby Brine Shrimp
Live Baby Brine Shrimp

Update: Endler Fry Tank 5 Months Later

After setting this tank up I added dwarf water lettuce which has spread to cover most of the surface. The java moss has more than tripled in size and now hosts a colony of blue dream shrimp in addition to multiple generations of Yellow Tiger Endlers.

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Mechanical Filter Media Basket
Mechanical Filter Media Basket

This mechanical media basket holds filter floss pads and Polyfil where water enters the sump on my 90 gallon rainbowfish aquarium. It is made from a plastic tupperware container that I up-cycled from a package of lunch meat (after washing thoroughly). I drilled about 30 holes into the bottom of the container using both a 1/8" and 1/4" bit to spread the flow evenly across the tray.

This is a modification to the original design for my DIY 20 gallon sump. The container fits perfectly into the larger basket that houses a coarse sponge and previously held my mechanical media. A smaller media tray keeps the flow of water concentrated into a reduced surface area, which allows me to use less mechanical media. It also facilitates changing the media, because it is easily removed and replaced, as shown in the video below.

The bottom of the basket is stuffed with Polyfil which is then covered by a piece of filter pad media that is cut slightly larger than the aperture of the container. The clear sides allow me to see when the media is dirty and needs to be changed. This is a dirt cheap DIY  mechanical filtration solution for a sump; I covered the use of Polyfil and some other cheap DIY filtration solutions here.