Redfield is relatively new to me and not being one to be exact on anything and preferring to take a more holistic view then knowing exact ratios might have started as a need but now based on actual application have some to the conclusion that it may not.
Been running an experiment with a 20H using a DIY undergravel plate that provides contact as it pulls water from the one end of the tank to the other under four inches of pumice coupled with about an inch of coral skeletons on top to assist with nitrification. Goal was to exhaust DO in order to allow denitrification to take place. This was working early on but since I don’t perform WCs or remove detritus other than what gets trapped in a small floss section surrounding GAC that builds up over time. Fact is used a Turkey baster to disturb the rocks and water became quickly cloudy to the point visibility was near zero confirming there’s detritus yet to be decomposed and can only assume there must be a large volume under the gravel plate.
What I’ve learned. Detritus takes longer to decompose then assumed or perhaps I’m not supplementing with enough heterotrophic bacteria. Something I have been doing periodically but not on a schedule. Mostly when nitrates start to climb. Use MB7. Nassarius snails added don’t seem to be feeding on it. Amphipods added don’t seem to be feeding on it. Thought was that as detritus decomposes it would naturally release carbon needed for denitrification. The latter part I’ve understood was needed before learning about Redfield and from back in the 80s when I first started studying denitrification knew that a source of food was required. At the time didn’t know it was carbon.
Besides the rate at which detritus decomposes, I’ve learned that ammonia and nitrites have not spiked. Early on in order to lower nitrates I added phosphates which was the catalyst as oddly my tank is phosphate deprived unless my nitrates rise. Haven’t figured that one out yet since I don’t run GFO and only time I’ve run PhosGuard was due to a high level of diatoms early on. Could have just let it run it’s coarse but I wanted to see how quickly that worked since I’m 50 plus years of keeping fish this was my first having it.
These days I’m forced to use NoPox to lower my nitrates and phosphates. Won’t go down naturally regardless of flow. Idea is that slower flow increases contact time to allow nitrification to reduce DO and allow denitrification to persist. Worked when my level of detritus was lower best I can assume.
As to the ratios. Seems that as long as you have one or the other but not both then neither go down. My experience. As to exact ratio that hasn’t seemed to matter plus I expect these values change through out the day based on last feed and probably something that can’t be accurately pinned down. However, raising that which is deficient has lowered both. Have come the the conclusion that having the current assumption of 100:16:1 carbon:nitrogenhosphorus or converted to what we test of 100:10:1 carbon:nitratehosphate might not be required. Simply elevating that which is low to get the other to be removed naturally. Although carbon needs to be added and at some point decomposition of detritus won’t be fast enough to provide latter which then must be added manually.
Some observations that I often see mentioned and I’m not experiencing.
Yes you can dose NoPox without a skimmer. Initially water will get cloudy for a few days. If excessive, fish will be seen breathing heavy. My recommendation is to add half or less than needed then increase slowly over the week. Skimmer not needed to remove the excess assumed bacteria. I don’t.
After initial doses, the dosage can be increased to double recommendation which out concern. At one point I’ve added 4 ml daily to approximately 16 gallons of tank volume.
Post Fishless cycle, I added 15 ml of NoPox. Since there were no fish. It was a quick way to reduce nitrate to near zero and avoid a costly and unnecessary WC. Water did get cloudy quickly. MB7 was added. Two or three days later it was crystal clear. Did have to add phosphates, however to finally bring nitrates down. Head scratcher until that was done. Don’t recall the amount but I aimed for bringing it to 4 ppm to match that recommended 10:1 ratio. Wa never able to record higher than 2 ppm but nitrates were already less than half prior and perhaps much consumed.
At some point if funds are available, I’d like to setup a Fishless system with ammonium chloride, nitrates and phosphates along carbon dosed as needed along with an automatic tester to see how these interactions occur. Although being one who loses interest in getting it exact this is likely not occurring. I’ll just take results off the main display which hopefully has an automatic tester. The latter has always been a pain for me to do religiously. More of look and evaluate what’s happening kind of guy. Knowing that isn’t always accurate or best.
Been running an experiment with a 20H using a DIY undergravel plate that provides contact as it pulls water from the one end of the tank to the other under four inches of pumice coupled with about an inch of coral skeletons on top to assist with nitrification. Goal was to exhaust DO in order to allow denitrification to take place. This was working early on but since I don’t perform WCs or remove detritus other than what gets trapped in a small floss section surrounding GAC that builds up over time. Fact is used a Turkey baster to disturb the rocks and water became quickly cloudy to the point visibility was near zero confirming there’s detritus yet to be decomposed and can only assume there must be a large volume under the gravel plate.
What I’ve learned. Detritus takes longer to decompose then assumed or perhaps I’m not supplementing with enough heterotrophic bacteria. Something I have been doing periodically but not on a schedule. Mostly when nitrates start to climb. Use MB7. Nassarius snails added don’t seem to be feeding on it. Amphipods added don’t seem to be feeding on it. Thought was that as detritus decomposes it would naturally release carbon needed for denitrification. The latter part I’ve understood was needed before learning about Redfield and from back in the 80s when I first started studying denitrification knew that a source of food was required. At the time didn’t know it was carbon.
Besides the rate at which detritus decomposes, I’ve learned that ammonia and nitrites have not spiked. Early on in order to lower nitrates I added phosphates which was the catalyst as oddly my tank is phosphate deprived unless my nitrates rise. Haven’t figured that one out yet since I don’t run GFO and only time I’ve run PhosGuard was due to a high level of diatoms early on. Could have just let it run it’s coarse but I wanted to see how quickly that worked since I’m 50 plus years of keeping fish this was my first having it.
These days I’m forced to use NoPox to lower my nitrates and phosphates. Won’t go down naturally regardless of flow. Idea is that slower flow increases contact time to allow nitrification to reduce DO and allow denitrification to persist. Worked when my level of detritus was lower best I can assume.
As to the ratios. Seems that as long as you have one or the other but not both then neither go down. My experience. As to exact ratio that hasn’t seemed to matter plus I expect these values change through out the day based on last feed and probably something that can’t be accurately pinned down. However, raising that which is deficient has lowered both. Have come the the conclusion that having the current assumption of 100:16:1 carbon:nitrogenhosphorus or converted to what we test of 100:10:1 carbon:nitratehosphate might not be required. Simply elevating that which is low to get the other to be removed naturally. Although carbon needs to be added and at some point decomposition of detritus won’t be fast enough to provide latter which then must be added manually.
Some observations that I often see mentioned and I’m not experiencing.
Yes you can dose NoPox without a skimmer. Initially water will get cloudy for a few days. If excessive, fish will be seen breathing heavy. My recommendation is to add half or less than needed then increase slowly over the week. Skimmer not needed to remove the excess assumed bacteria. I don’t.
After initial doses, the dosage can be increased to double recommendation which out concern. At one point I’ve added 4 ml daily to approximately 16 gallons of tank volume.
Post Fishless cycle, I added 15 ml of NoPox. Since there were no fish. It was a quick way to reduce nitrate to near zero and avoid a costly and unnecessary WC. Water did get cloudy quickly. MB7 was added. Two or three days later it was crystal clear. Did have to add phosphates, however to finally bring nitrates down. Head scratcher until that was done. Don’t recall the amount but I aimed for bringing it to 4 ppm to match that recommended 10:1 ratio. Wa never able to record higher than 2 ppm but nitrates were already less than half prior and perhaps much consumed.
At some point if funds are available, I’d like to setup a Fishless system with ammonium chloride, nitrates and phosphates along carbon dosed as needed along with an automatic tester to see how these interactions occur. Although being one who loses interest in getting it exact this is likely not occurring. I’ll just take results off the main display which hopefully has an automatic tester. The latter has always been a pain for me to do religiously. More of look and evaluate what’s happening kind of guy. Knowing that isn’t always accurate or best.