What Exactly Is A Ph Crash?

[mossonthemoon]

I am just wondering whether a pH crash (in terms of getting a cycle completed) is when it drops a lot from whatever it is normally, or when it goes below a certain level? What is the lowest it should be if that is what it is? I am a bit worried about my pH right now, but doing another test because my results didn't make sense.

Update: I just tested four times: twice for both pH tests. The high pH seems to give a slightly off-colour but near 7.4 reading, and the normal pH test is coming out yellow, so 6.0. How do I know which one to trust? This would explain my seemingly slowed cycle, if it is a pH crash.

 

[crazyforcordoras]

I Ph crash is indeed when yoir ph lowers drastically at once. For example your Ph starts as 7.6 then it lowers to 6.0.

 

[Gvilleguy]

Hi Mosso - the high pH test only goes down to 7.4, so you always take the lower reading of the two. Your pH is currently 6.0. Assuming you are doing a fishless cycle, then the bacterial growth process REALLY slows down then pH gets down to 6.0 to 6.4. Without fish in the tank, it is perfectly safe to use bicarbonate of soda to temporarily get the pH level back up.

 

[mossonthemoon]

Ugh, thanks. I thought so, but hoped for better news. This has never happened in a tank of mine before. My pH was high before - 7.8 as far as I can remember, but definitely in the high 7s at least. How much should I add to a 180 litre tank? It is in a fishless cycle.

 

[mossonthemoon]

Ah, I managed to open another thread about it (the forum isn't working well on my side), and someone suggested 3 tablespoons. I will go with that, I think.

 

[mossonthemoon]

Well this morning my pH was between 7.4 on the normal test and 7.6 on the high pH, so I will assume it is somewhere in there, which is much better. My nitrites were 0, ammonia was a slightly dark 0.25, and nitrates were maybe 20-30. For some reason I have a more difficult time reading the nitrates but I know it is probably not terribly accurate anyway. This is a huge improvement from 6.0 pH and 3.0 ammonia last night. What a relief!

 

[Gvilleguy]

Good job on recovering! Agree that nitrates can be hard to read.