Being familiar with the 2007 Tetra Patent on the use of PCL's (polycaprolactone) in Aquaria to achieve denitrification, and watching them waste it by not introducing any serious product, I was happy to see Dr. Tim's release a product last year (I think) called Dr. Tim's NP-Active Pearls that utilize PHAs instead of PCLs. About 5 weeks ago, I decided to try these in my moderately stocked 100 gallon Oscar tank (14" Oscar, 5 full sized Silver Dollars) in an effort to minimize nitrate creep. A little prerequisite information:
- Biopolymers (in this case, PHAs in the form of Dr. Tim's NP Active Pearls) act as both a source of organic carbon and as a home for denitification bacteria
- In order to use NP Active Pearls, they need to be located in a reactor, under constant motion.
- The denitrification bacteria that develops on the pearls utilizes organic carbon found in the Pearls themselves as an energy source.
- In addition to Nitrates, this process consumes phosphate from the water. If phosphate is depleted, nitrate reduction will cease to occur.
- This process occurs aerobically. It does not require anaerobic conditions.
- As the bacteria consume the pearls and nitrates, they grown in population, and must be exported from the tank before they die and break back down, re-releasing the nitrate they have consumed.
In saltwater systems, this "'export" is achieved via the use of protein skimmers. In freshwater, it occurs using mechanical filtration.
For my Oscar tank, I constructed a DIY Mechanical Trickle Filter out of a plastic flower box, using a Spraybar for an Eheim 2217, redneck engineering the following contraption that sits atop my sump. The outflow from the reactor containing the Pearls empties into this filter.
The above "flowerbox filter" contains multiple layers of mechanical filter media. From top to bottom, it contains:
Blue Bonded Padding
Sera Filter Wool
1" Super Fine Filter Pad (from Drs. Foster and Smith"
200 Micron filter pad
100 Micron Filter pad
50 Micron Filter pad.
The Pearls themselves are housed in an inexpensive Phosban reactor (with both prefilter sponges removed, this is important) driven by a 500gph mag drive pump.
Below is a link to a short video of the setup at work.
http://www.youtube.com/watch?v=Y4yu6Va2QEM
The following image is an example of nitrate creep on this tank prior to adding NP-Pearls. Following a 100% water change, nitrate creep historically averages out to about 10ppm per week.
The end result of this experiment, as documented in the below image, is that in the 4th week of using NP Active Pearls, Nitrates creep is basically eliminated in this tank.
So, it is obvious Dr. Tim's NP Active Pearls work in freshwater, but there are a few things you need to be aware of. First off, do not underestimate the amount of slime this process produces. If you attempt to simply add NP Active Pearls to your tank without the added step of the outflow reactor going through a separate mechanical filter, be prepared for your primary filters to start clogging up in weeks and (potentially) brown slime accumulating on the substrate, ornaments, and grass. I started at 200 Micron and worked my way further down to 50 Micron, because at 200 Micron and 100 Micron, the stuff was still making it into my filters. Secondly, I am currently performing a daily cleaning of the top layers of the filter media in the "Flowerbox filter", with weekly cleanings of all media in the filter. While I currently do not know how long you can wait between cleanings without reintroducing nitrates (i will be learning that in the upcoming weeks), If you are one of these who only want to clean something of this nature once a month or every few months, forget about it. This is not for you. The bacterial slime in the mechanical filter media must be cleaned frequently, otherwise as it decomposes it will release the nitrates (and phosophates) that have been consumed back into the water and you've gained nothing (not to mention it stinks). The higher the nitrates and the more the nitrate creep, the more prolific will be the resulting slime.
Aside from the slime, which is managed via the Flowerbox filter and frequent cleanings, there have been no negative side effects. In fact, one of the huge benefits in my circumstance is improved tank stability. My tap water is very soft with a KH of only 2dGH. While nitrification erodes the carbonate buffer, completed denitrification replenishes it, so even with a KH as low as mine there is no danger of a pH crash as long as denitrification is working.
A decade ago, I called simple denitrification the holy grail of fish keeping. But here you go. Simple and safe denitrification that anyone can achieve.
- Biopolymers (in this case, PHAs in the form of Dr. Tim's NP Active Pearls) act as both a source of organic carbon and as a home for denitification bacteria
- In order to use NP Active Pearls, they need to be located in a reactor, under constant motion.
- The denitrification bacteria that develops on the pearls utilizes organic carbon found in the Pearls themselves as an energy source.
- In addition to Nitrates, this process consumes phosphate from the water. If phosphate is depleted, nitrate reduction will cease to occur.
- This process occurs aerobically. It does not require anaerobic conditions.
- As the bacteria consume the pearls and nitrates, they grown in population, and must be exported from the tank before they die and break back down, re-releasing the nitrate they have consumed.
In saltwater systems, this "'export" is achieved via the use of protein skimmers. In freshwater, it occurs using mechanical filtration.
For my Oscar tank, I constructed a DIY Mechanical Trickle Filter out of a plastic flower box, using a Spraybar for an Eheim 2217, redneck engineering the following contraption that sits atop my sump. The outflow from the reactor containing the Pearls empties into this filter.
The above "flowerbox filter" contains multiple layers of mechanical filter media. From top to bottom, it contains:
Blue Bonded Padding
Sera Filter Wool
1" Super Fine Filter Pad (from Drs. Foster and Smith"
200 Micron filter pad
100 Micron Filter pad
50 Micron Filter pad.
The Pearls themselves are housed in an inexpensive Phosban reactor (with both prefilter sponges removed, this is important) driven by a 500gph mag drive pump.
Below is a link to a short video of the setup at work.
http://www.youtube.com/watch?v=Y4yu6Va2QEM
The following image is an example of nitrate creep on this tank prior to adding NP-Pearls. Following a 100% water change, nitrate creep historically averages out to about 10ppm per week.
The end result of this experiment, as documented in the below image, is that in the 4th week of using NP Active Pearls, Nitrates creep is basically eliminated in this tank.
So, it is obvious Dr. Tim's NP Active Pearls work in freshwater, but there are a few things you need to be aware of. First off, do not underestimate the amount of slime this process produces. If you attempt to simply add NP Active Pearls to your tank without the added step of the outflow reactor going through a separate mechanical filter, be prepared for your primary filters to start clogging up in weeks and (potentially) brown slime accumulating on the substrate, ornaments, and grass. I started at 200 Micron and worked my way further down to 50 Micron, because at 200 Micron and 100 Micron, the stuff was still making it into my filters. Secondly, I am currently performing a daily cleaning of the top layers of the filter media in the "Flowerbox filter", with weekly cleanings of all media in the filter. While I currently do not know how long you can wait between cleanings without reintroducing nitrates (i will be learning that in the upcoming weeks), If you are one of these who only want to clean something of this nature once a month or every few months, forget about it. This is not for you. The bacterial slime in the mechanical filter media must be cleaned frequently, otherwise as it decomposes it will release the nitrates (and phosophates) that have been consumed back into the water and you've gained nothing (not to mention it stinks). The higher the nitrates and the more the nitrate creep, the more prolific will be the resulting slime.
Aside from the slime, which is managed via the Flowerbox filter and frequent cleanings, there have been no negative side effects. In fact, one of the huge benefits in my circumstance is improved tank stability. My tap water is very soft with a KH of only 2dGH. While nitrification erodes the carbonate buffer, completed denitrification replenishes it, so even with a KH as low as mine there is no danger of a pH crash as long as denitrification is working.
A decade ago, I called simple denitrification the holy grail of fish keeping. But here you go. Simple and safe denitrification that anyone can achieve.
