Why can I not kick Ammonia?

[digital-audiophile]

I am somewhat baffled as to why I cannot drop the Ammonia level in my new tank.

Current readings

Ammonia : 0.5
Nitrite : 0.0
Nitrate : <30
PH : 7.8

I have had the tank (90G) cylcing for 6 weeks now. I have >100lbs of live rock in there 1/3 cooked rocked, 1/3 rock from my existing tank and another 1/3 of new rock from Red Coral and Elite.

I've been testing the tank every couple of days and these reading have been consistant for about 2 weeks now. I have used two ammonia test kits to make sure I was not getting a false reading. My PH is low too but I have started dosing with a PH buffer to help bring it up.

It just seems odd to me that I continue to test 0 Nitrites and high nitrates but still have trace Ammonia?

[Delphinus]

What test kits are you using?

I think you're getting false positives. Have you been able to test any SW and get a zero reading?

[Delphinus]

Incidentally I don't think you want to use a buffer to raise the pH. The pH does seem a little low but it's not unreasonably low. If you run a calcium reactor for example it's not uncommon to have a tank pH of 7.8-7.9. I'd be curious to see what your alk and Ca levels are at because that might help explain the pH. Also it's a bit odd to me to see nitrate expressed as "less than 30", 30 is practically astronomical for a reef (maybe not so for a FO, but for a reef, that's pretty high). Does the test kit not provide lower resolution? I guess it comes back to now I'm wondering what test kits you're using.

As for the pH though, pH is more of an indicator of what things are going on in the tank. Additives that raise or lower the pH are only treating a symptom. To me it's a little like saying I will warm up the thermometer to get it to show me a warmer temperature, rather than raising the ambient temperature outside. Also the natural processes going on in a tank will affect pH. For example if you test first thing in the morning it will be low, if you test at high noon it will be higher.

[PoonTang]

Your tank is still young give it time. Are there any critters in it yet? Sand? Are you doing any water changes? Do an ammonia and nitrite test on new salt water to see if it is your kits. Do NOT use buffer to try and correct pH issues, only add buffer when your tests indicate that hardness is low. Again, your tank is still young so it is not unreasonable to expect that some of your numbers may be out of wack a little.

[digital-audiophile]

I'll get the name of the test at home.. for some reason it is eluding me right now I've used two different kits though (same manufacturer) so I dont think it might not be a false negative

I am using instant ocean salt (same bucket that I use on my old tank without issues) I'll test the source water tonight too.

I used 30+ lbs of new sand but seeded it with sand from my other tank.

I'll clarify the nitrate level when I am home as well the test marker only gives in 20PPM incriments if I recall correctly.

I've been changing about 20 Gallons of water each week since I started cycling.

The only life in the tank right now are a dozen snails and a couple hermits. I have been waiting for the tank to cycle before I move three fish over from my other tank (I am closing it down as I traded it for the 90 and want to finish my end of the deal.)

I'll also tesk for alk and calcium tonight.

Thanks for the advice guys, keep it coming

[ponokareefer]

If you normally shop at a particular LFS, you could take a sample of your water down to them and have them test it for you. That will rule out for sure if your tests are both wrong.

[Delphinus]

I actually would not rule out the false positive still Greg. Some test kits just aren't very robust, although they may say "good for FW or SW" they're not really that good in SW. I never test for ammonia. I do have an ammonia test kit though that will always give a low non-zero value in SW.

Just for kicks, test for ammonia on your old tank. I'm willing to bet you get a positive value on that one. By your nitrite and nitrate values, that tank is has finished its initial cycle. If you had ammonia, you would have nitrite.

In fact, it's almost pointless to test ammonia. It's only in the most serious of tank crashes, or massive death events, that you'd get an ammonia reading anyhow. In 9 years of keeping reefs I've never really had to test for ammonia, and the one time I thought I did, I was completely baffled by the fact that I was showing an ammonia reading when in fact it was a false positive and the problem was something else. I don't even remember what it was, but I remember thinking "why does the ammonia reading always read "X" no matter what I do?"

I'm thinking you may want a different nitrate test kit too. Increments of 20 isn't very high resolution. A reef you want nitrates to be under 10 (not really a hard and fast rule, but typically, a reef has very low nitrates like 2 to 5 ish). The Salifert ones are not bad, the Elos ones are pretty good too. I used to use Seachem and they weren't too bad but I haven't seen them for sale anywhere for a while.

[hawk]

Six weeks is not out of the question to still be cycling. I just finished cycling a qt tank and it took 6 -7 weeks (left a couple of frozen shrimp in a bit too long). Water changes during a cycle are not required and will only lengthen the cycle time.

[Delphinus]

Ordinarily I would agree with you hawk but his nitrite numbers are zero and his nitrate values are climbing. If the tank had not completed its ammonia cycle, it would not have completed its nitrite cycle and there would be a non-zero value for nitrite.

Now, it's possible that the nitrite test kit is giving a false negative, but IMHO this is less likely than an ammonia test kit giving a false positive. If the ammonia reading is non-zero but low (ie. close to zero) and unchanging over a long period of time, I would distrust that reading. If it is changing then it is likely valid, but unchanging is suspect, espescially if nitrite is zero.

FWIW some people will start up a new tank with existing rock and existing water and start stocking it the next day. Basically If you have the appropriate mass of rock a cycle can be very quick. With over 100lbs of rock (so over 1lb/gal), with 2/3 being cycled rock already .... I think it's a pretty safe bet that his initial cycle is done.

Tell you what, here's a real acid test, throw a frag of something like GSP or zoos or something in the tank and see how they do. If there's ammonia they won't open up, if they do open up though then it's probably safe to start moving other things in there.

[Quagmire]

I talked to Greg a couple weeks ago and he mentioned these readings.At the time I thought perhaps it was a smaller cycle starting due to bacteria die off.But now with no change I'm leaning towards the test kit also.At the worst a good test kit will strike one possibility off the list.