The long and skinny of my issue is that I have something leaching from the sand I use as my substrate that is causing an alarmingly high false reading using a salicylate based ammonia test kit (API specifically, but any test using this chemistry will most likely provide the same results). I need help identifying what this mystery substance could be.
Some more background and details are defnitely in order. I just wanted to get the main question out there on top for those that are just skimming things. I have about 25 years of increasingly knowledgeable fishkeeping experience under my belt, and have been running a 25 gal continuously without any major issues for the past 20 years. I also have a newer 55 gal running now that is established and has been in operation for about 8 months now. The 25 gal is currently a welcome tank for new arrivals to spend their first few months in and is bare bottom. No issues in there. The 55 gal, though, has a sand bottom that has been causing me some grief. It is a pure silica pool filter sand I get from a local sand and gravel operation called Shaw Resources (Nova Scotia, Canada). It's really an excellent sand that both the fish and I just love. I researched the sand before I started using it and inquired about any additives they might use that might pose a problem. It's just pure silica sand. It leaches a little bit of silicates into the water that makes the tank more hospitable to brown algae, but I easily keep that in control with a little Phosbond in the filter. The big problem is that it seems to be leaching something into the tank that is giving me a false positive reading on my ammonia test kit.
When I first established the tank, for several months all was good. Then I decided to replace my test kit reagents as the ones I were using were getting quite old. I nearly had a heart attack when I did my first ammonia test with the new kit and it basically turned black on me. Well, dark green to be exact, but the darkest reading the test can give. So I immediately repeated the test several times assuming I had messed the first one up royally, but kept getting the same result. So I tested a bunch of other water sources - taps, buckets, my 25 gal - thinking I just had a faulty kit, but got the expected 0 ppm result each time. I even tried a fresh test with the old kit and it was reading just a slight hint of ammonia itself. So I had missed the slowly accumulating problem because I was using a test kit not sensitive enough any more to detect it and jumped right into the middle of the problem with both feet. The health and behaviour of the fish has never been affected, so the through that I actually had 8+ ppm of ammonia in my tank never really held any validity to me. Everything in the tank would be long dead at those levels. I have had no deaths and the fish all appear to be healthy and normal.
Fast forward through 3 days of research and testing and I have definitively proven that the source of the high ammonia reading is the sand, and it is almost certainly not actually ammonia. I soaked some of the sand in some pure water for a while and was able to get a positive test result for ammonia from the water. The sand used in the test was from the same bag as what's in the tank but had never been used in the tank. There is some substance leaching from this sand that is causing the API salicylate based ammonia test kit to detect ammonia, but whatever it is is having no appreciable impact on the fish. Now that I am aware of it I am keeping the levels low through increased frequency and quantity of water changes, but this is not a great long term solution. I would much rather figure out what's going into the water and how to get it out. What could it be that is causing the ammonia test to react? Copper was my first suspect, but on testing the water is reading 0 ppm of copper. If the culprit is a metal, perhaps Cuprisorb would still help to remove it? Cuprisorb adsorbs a lot of different dissolved metals besides just copper. It might be worth a shot, but the stuff is pretty pricey so I'd really like some input before trying that route.
So, any theories on what my mystery substance might be? Anybody have any similar experiences with false positive results on these test kits that didn't end up coming back to copper or Prime? All input is welcomed and any insights are greatly appreciated. I will keep the thread up to date with any new developments.
Some more background and details are defnitely in order. I just wanted to get the main question out there on top for those that are just skimming things. I have about 25 years of increasingly knowledgeable fishkeeping experience under my belt, and have been running a 25 gal continuously without any major issues for the past 20 years. I also have a newer 55 gal running now that is established and has been in operation for about 8 months now. The 25 gal is currently a welcome tank for new arrivals to spend their first few months in and is bare bottom. No issues in there. The 55 gal, though, has a sand bottom that has been causing me some grief. It is a pure silica pool filter sand I get from a local sand and gravel operation called Shaw Resources (Nova Scotia, Canada). It's really an excellent sand that both the fish and I just love. I researched the sand before I started using it and inquired about any additives they might use that might pose a problem. It's just pure silica sand. It leaches a little bit of silicates into the water that makes the tank more hospitable to brown algae, but I easily keep that in control with a little Phosbond in the filter. The big problem is that it seems to be leaching something into the tank that is giving me a false positive reading on my ammonia test kit.
When I first established the tank, for several months all was good. Then I decided to replace my test kit reagents as the ones I were using were getting quite old. I nearly had a heart attack when I did my first ammonia test with the new kit and it basically turned black on me. Well, dark green to be exact, but the darkest reading the test can give. So I immediately repeated the test several times assuming I had messed the first one up royally, but kept getting the same result. So I tested a bunch of other water sources - taps, buckets, my 25 gal - thinking I just had a faulty kit, but got the expected 0 ppm result each time. I even tried a fresh test with the old kit and it was reading just a slight hint of ammonia itself. So I had missed the slowly accumulating problem because I was using a test kit not sensitive enough any more to detect it and jumped right into the middle of the problem with both feet. The health and behaviour of the fish has never been affected, so the through that I actually had 8+ ppm of ammonia in my tank never really held any validity to me. Everything in the tank would be long dead at those levels. I have had no deaths and the fish all appear to be healthy and normal.
Fast forward through 3 days of research and testing and I have definitively proven that the source of the high ammonia reading is the sand, and it is almost certainly not actually ammonia. I soaked some of the sand in some pure water for a while and was able to get a positive test result for ammonia from the water. The sand used in the test was from the same bag as what's in the tank but had never been used in the tank. There is some substance leaching from this sand that is causing the API salicylate based ammonia test kit to detect ammonia, but whatever it is is having no appreciable impact on the fish. Now that I am aware of it I am keeping the levels low through increased frequency and quantity of water changes, but this is not a great long term solution. I would much rather figure out what's going into the water and how to get it out. What could it be that is causing the ammonia test to react? Copper was my first suspect, but on testing the water is reading 0 ppm of copper. If the culprit is a metal, perhaps Cuprisorb would still help to remove it? Cuprisorb adsorbs a lot of different dissolved metals besides just copper. It might be worth a shot, but the stuff is pretty pricey so I'd really like some input before trying that route.
So, any theories on what my mystery substance might be? Anybody have any similar experiences with false positive results on these test kits that didn't end up coming back to copper or Prime? All input is welcomed and any insights are greatly appreciated. I will keep the thread up to date with any new developments.
