Ammonia dropped suddenly - cycle ending?

Gomisan

Gomisan

Man in a hat
Feb 9, 2006
109
0
0
Adelaide, South Australia
www.ufo-x.com
I've been taking daily readings from my tank as I've attempted to babysit it through it's cycle.

Today the ammonia has dropped considerably, but I haven't fed the fish.... so I'm not sure, would the drop in the ammonia be because my cycle is almost over, or because i've reduced the food and hence waste products? Obviously I'll keep monitoring it, but I'm just hoping this is the light at teh end of the tunnel.

As an example, here's the readings from the past few days, (I don't yet have a Nitrite test kit):

22/2 (normal feeding)
Ammonia: 3.7
pH: 8.0
Nitrate: 10mg/L

23/2 (normal feeding)
Ammonia: 3.7
pH: 7.5
Nitrate: 20mg/L (I dont have a Nitrite test kit yet)

24/2 (fed about 1/2 what I had been)
Ammonia: 2.4
pH: 7.5
Nitrate: 50mg/L

25/2 (not fed today)
Ammonia: 0.3
pH: 7.0
Nitrate: 110mg/L

All readings are taken in the afternoon, before doing a water change. The tank is now 20 days old.
 
Your pH is dropping like a stone… that's not good.

Do you know your KH? How big of a water change? A pH crash at this point could wipe out your cycle…

It looks to me like you're passing out of the ammonia phase. Nitrates that high indicate that there's lots of nitrites and they're being processed. Ideally you'd want to keep them at least under 40 (mg/l or ppm, same thing). Many would say lower than that. Cycle is done when Nitrites are also at zero.
 
Carpguy is correct on all counts and yah, that pH drop is very alarming.

Please get a KH kit and test your KH asap. Test the tap and your tank.

Do a 50% water change as well and get the pH back up where it should be. Until you get a kit, if you see that pH drop below 7.5, do a 50% change and get it back to 8.0

Assuming there is no pH buffer present, if your pH drops to ~6.0, then you will lose all the bacteria you have established. If your pH is somehow being buffered, then we have no idea what it should be and what the danger zone really is.

This sounds familar, did we go through this already? N/M, we were talking about your school's tank GH. ;)

Roan
 
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It's really late, so thanks for the answers, and I'll get back to you with other readings when I wake up :coffee:

I have been doing the occasional KH test, and the pH is REALLY hard to gauge with the hagen colour samples, so it may not have changed as much as that looks. Next pay I'll probably invest in one of those elcetronic pH testers.

The water changes have been a pretty consistent 20-25% (about 9 to 10L)

and yes this is my home tank, not the work one.

One thing that seems positive to me is that all the fish are still active and 'seem' happy, and there is still a Glass Shrimp hanging about, and I hear they can be quite sensitive.
 
hey roan, i'm thinking that the ph level for loosing bateria is like 5.5, not 6, but i could be wrong. but yeah that's still not good. also possible using a buffer like ph up, in a small amount or some cc mixed in with the substrate could help, long term.
 
I'm trying to use as few chemicals as possible, because with such a small tank the balance is going to be hard enough to maintain as it is.

Also, I think the change in pH may be a reflection of the abscence of Ammonia, surely the fact that Ammonia is an alkaline and was in such high quanities in the tank would have been skewing the pH readings while it was spiking.

For the record, the new tank, before the Ammonia spike was giving consistent pH 7.5 readings, it only went to 8 while the Ammonia was there. Also, it's so hard to tell the difference betwen 7.0 & 7.5 with the Hagen test that it's more likely in the middle of the two :cool:

The Tapwater readings:
pH: 7.0
KH: 40 mg/L

Today's Tank Readings:
pH: 7.5
KH: 40mg/L
Ammonia: 0 to 0.1
Nitrate: 110+ (this is my new worry, another water change today!)
 
Ok.. ths is weird. I did a 20 % water change after that high Nitrate reading, yet today when I tested Nitrate, it was down around 5mg/L !! So I tested it again.. yep, it's all gone.

So can a 20% water chaneg have that big an effect? or could it be that my plants are chewing it up?

or.. are th tests just that inacurate? I still don't have a Nitrite test kit, so perhaps a final Nitrite spike was skewing readings? and now teh Nitrite bacteria have munched all that too?

I'm confused. :)

more research... :read:

at least the fish seem OK still.. I think it's going to be fine, just puzzled is all.
 
First off, you should prob get a nitrite test kit. Also, are you using strips to test, or the liquid? Strips are notoriously inaccurate. No way would a 20% water change drop your nitrates from 110ppm to 5 ppm. Whats the nitrate reading of your tap water?
 
Ammonia is not responsible for the changes in pH directly, but rather indirectly through the reduction in KH as the bacteria consume the ammonia.

Plants will make a big difference in both ammonia and nitrate levels. They preferentially will use ammonia, though, short cutting the process.
 
reduction in KH as the bacteria consume the ammonia.
Click to expand...

Ammonia bacteria "eat" KH (Carbonates/Bicarbonates)?

Hold on a sec...

How did I miss that?!?!?!

Are you sure about that OG?
 
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