First saltwater Tank, Not sure if my tank is fully cycled.

[jayjlb52]

Hi, All

I have few questions about cycling a saltwater tank. I’ve been cycling a 29Gal tank for about 25 days. My PH has been holding steady at 8, Nitrates are >160ppm, and After dosing 2ppm Ammonia, the Ammonia drops to 0 in about 12hrs but it takes the Nitrite about 36hrs to clear. Is my cycle done or should I keep dosing at 0 Ammonia and Nitrite?

How often and how much water can I change to get my nitrates down?

 

[Azedenkae]

Hi, All

I have few questions about cycling a saltwater tank. I’ve been cycling a 29Gal tank for about 25 days. My PH has been holding steady at 8, Nitrates are >160ppm, and After dosing 2ppm Ammonia, the Ammonia drops to 0 in about 12hrs but it takes the Nitrite about 36hrs to clear. Is my cycle done or should I keep dosing at 0 Ammonia and Nitrite?

How often and how much water can I change to get my nitrates down?

Whew, how much ammonia did you dose to get nitrate that high lol.

Also, is that the measurement when ammonia and nitrite already reads 0?

Anyways, a few things.
1. I personally prefer to have both ammonia and nitrite read 0 within 24 hours of dosing ammonia, just to be sure. But that's not exactly always necessary, because,
2. Nitrite is non-toxic to marine fish and stuff unless it reaches pretty high levels. For ocellaris clownfish, a study had suggested to keep nitrite below 25ppm, as prolonged exposure above that can cause lesions and stuff, though nitrite needs to be way higher than that to cause deaths. So,
3. Even though your nitrite might increase slightly after you add live stock, imo your nitrite oxidizers are reproducing fast enough at this point that you won't ever reach 25ppm nitrite, or even close.
4. I'd say probably around 20ppm nitrate would be a good point to reach, but that's a 87.5% water change minimum, which is kinda... a lot. I mean at that point might as well do a 100% water change, but yeah, a lot. Personally, I would do it, cause otherwise you gotta find some other means to lower nitrate, like setting up algae scrubber or whatever. I would not recommend doing small water changes, because that just takes wayyyyy too much time and resources. To reduce nitrate by the same amount as a 87.5% water change, you'd need to do 9 20% water changes, so that's 180% water you'd need to make in total. However, make sure that,
5. When you measure nitrate you also measure nitrite and be sure that nitrite reads 0. Because most nitrate test kits actually convert a portion of nitrate to nitrite first, then measures based on that so if there is nitrite present, nitrate can read higher.
6. By the way, do you happen to know how much ammonia you dosed in total?

 

[Jekyl]

Tank is ready. Do a large water change to get nitrates down. I'd just figure at least a 75% change if not more. Easier to get the numbers in order now than when fish or coral are present.

 

[jayjlb52]

Whew, how much ammonia did you dose to get nitrate that high lol.

Also, is that the measurement when ammonia and nitrite already reads 0?

Anyways, a few things.
1. I personally prefer to have both ammonia and nitrite read 0 within 24 hours of dosing ammonia, just to be sure. But that's not exactly always necessary, because,
2. Nitrite is non-toxic to marine fish and stuff unless it reaches pretty high levels. For ocellaris clownfish, a study had suggested to keep nitrite below 25ppm, as prolonged exposure above that can cause lesions and stuff, though nitrite needs to be way higher than that to cause deaths. So,
3. Even though your nitrite might increase slightly after you add live stock, imo your nitrite oxidizers are reproducing fast enough at this point that you won't ever reach 25ppm nitrite, or even close.
4. I'd say probably around 20ppm nitrate would be a good point to reach, but that's a 87.5% water change minimum, which is kinda... a lot. I mean at that point might as well do a 100% water change, but yeah, a lot. Personally, I would do it, cause otherwise you gotta find some other means to lower nitrate, like setting up algae scrubber or whatever. I would not recommend doing small water changes, because that just takes wayyyyy too much time and resources. To reduce nitrate by the same amount as a 87.5% water change, you'd need to do 9 20% water changes, so that's 180% water you'd need to make in total. However, make sure that,
5. When you measure nitrate you also measure nitrite and be sure that nitrite reads 0. Because most nitrate test kits actually convert a portion of nitrate to nitrite first, then measures based on that so if there is nitrite present, nitrate can read higher.
6. By the way, do you happen to know how much ammonia you dosed in total?

I don’t recall checking Nitrates while Ammonia and Nitrite were both 0, I will do that today. I’ve dosed 2ppm Ammonia 8 times over 25days.

 

[Azedenkae]

I don’t recall checking Nitrates while Ammonia and Nitrite were both 0, I will do that today. I’ve dosed 2ppm Ammonia 8 times over 25days.

Mhm, yeah check nitrate while nitrite is 0 today. Dosing 2ppm ammonia 8 times would result in 16ppm in total, which would convert to around 58ppm nitrate. So it would be weird to see 160ppm nitrate, especially if you had none to begin with.

 

[jayjlb52]

Mhm, yeah check nitrate while nitrite is 0 today. Dosing 2ppm ammonia 8 times would result in 16ppm in total, which would convert to around 58ppm nitrate. So it would be weird to see 160ppm nitrate, especially if you had none to begin with.

I rechecked Nitrate while Nitrite is 0, and the API test kit is now giving a reading close to 80ppm. Also I did a 75% water change and will retest tomorrow. Thanks for the advice.

 

[Azedenkae]

I rechecked Nitrate while Nitrite is 0, and the API test kit is now giving a reading close to 80ppm. Also I did a 75% water change and will retest tomorrow. Thanks for the advice.

Yeah that makes more sense lol. XD I mean still higher than expected, but of course there could have been other confounding factors.

Either way, yeah 75% should get you down to 20ppm. I mean I'd recommend doing a test now after the water change, almost also as a validation of your nitrate test of sources as it should not read around 20ppm-ish. And then yeah, would be all good!

 

[attiland]

Well almost all sad already. Do a large water change and stop dosing ammonia.
Get proper nitrate and phosphate checker like Hanna. And throw the API kit away they are really bad and inaccurate.
If not already using RODI water get a unit to source the water
Get an auto top of system so salinity will be stable.

 

[jayjlb52]

Well almost all sad already. Do a large water change and stop dosing ammonia.
Get proper nitrate and phosphate checker like Hanna. And throw the API kit away they are really bad and inaccurate.
If not already using RODI water get a unit to source the water
Get an auto top of system so salinity will be stable.

I’m using RODI, and I’ll see if I can pick up a better test kit.

 

[jayjlb52]

Yeah that makes more sense lol. XD I mean still higher than expected, but of course there could have been other confounding factors.

Either way, yeah 75% should get you down to 20ppm. I mean I'd recommend doing a test now after the water change, almost also as a validation of your nitrate test of sources as it should not read around 20ppm-ish. And then yeah, would be all good!

Nitrate tested right at 20ppm just now.

 

[Azedenkae]

Nitrate tested right at 20ppm just now.

Perfect! P.S. You don't need new test kits, API test kits work fine. As you can tell - if not you'd have gotten readings that are very random by now, but it's all in line with what is expected.

The whole nitrite affecting nitrate test kit thing applies to most nitrate test kits on the market, so it's not like a 'better' test kit helps. XD