# cycling tank but pH keeps dropping...



## ryguy76 (Mar 11, 2013)

I am almost done my cycle, but my pH has dropped significantly. I recently did a 70%WC and it returned to 7.0 for a day, but today, it's sitting at 6.5.

I'd like to try using crushed coral in a bag within the HOB filter, and I have a 6G tank. 

A. how much would I need?
B. am I able to purchase this in a small amount?


----------



## crazy72 (Apr 22, 2010)

Is it a fishless cycle that you did? With pure ammonia?


----------



## ryguy76 (Mar 11, 2013)

yes. started with a raw prawn, but the small prawn i used ended up producing too much ammo. So I took it out and did a 50% WC. that brought the ammo down do 4ppm. then that was consumed and i put another raw prawn in, but never saw an ammo increase, probably because it was being consumed as it was being produced.

Then i switched to "Old Country" pure ammonia, and took the other prawn out. I've been dosing everyday to 4ppm, but someone else suggested that I only dose to 2ppm due to tank size.


----------



## crazy72 (Apr 22, 2010)

Right. The pH crash is normal. I experienced it myself in the past. See here for instance for explanations. ph fishless cycle question

If you do a large water change to bring the pH back up, and add ammonia again but just enough to bring the reading up, then it should be fine. If not, repeat . For me it worked after a couple of iterations.


----------



## MEDHBSI (Sep 4, 2011)

From my experience my understanding is you cant put to much crushed coral in a mesh bag because it gives of a ph of 7 so even if you put 20lb it would still keep it at 7. I use about 5lb in my 180g. I think it comes in a 20lb bag and its pretty dang cheap.


----------



## ryguy76 (Mar 11, 2013)

thanks.

so should I just dose to 1ppm then? I have yet to see nitrites...ever. but the nitrates are sitting between 40 and 80 after yesterdays 70% WC which brought the nitrates to zero, so I have to believe I have a faulty test, or it's getting converted to nitrate very quickly. Not sure how I'll know for sure that the cycle is done, but I figure if I can turn 2ppm of ammo into zero in 24 hrs while producing zero to 40-80ppm nitrates, I have to be close even without seeing nitrites.

Is 7.0pH a decent target? or should I be aiming for 7.4?


----------



## crazy72 (Apr 22, 2010)

Vary strange that you never saw nitrites. Is your test kit new? If not, I'd buy another one. How long have you been cycling? How long since the first prawn, for instance? And did you seed the tank with bacteria from another tank or did you start from scratch?

In terms of pH, I'd say that the pH you want to aim for depends on what fish/shrimp you want to keep.


----------



## MEDHBSI (Sep 4, 2011)

If you have nitrates you did at some point have nitrites but the bacteria that eats it is doing its job  your tank is fully cycled when you see 0 ammonia and 0 nitrite and a little or alot nitrates. It really depends on the fish you want to keep if you google the fish it should tell you a good ph. Most fish can live in any ph between 6-8 its the ph swings that kill fish. The crushed coral is there to make it stable so i doesn't go up and down. Is your tank a salt or fresh? do you have any wood in the tank?


----------



## ryguy76 (Mar 11, 2013)

It's been about 3.5 weeks since I started the cycle with the raw prawn, but did not seed it. It was indeed started from scratch.

I've tested for nitrites almost everyday after I started seeing ammo. at the most, it went 48 hrs without testing, but it's always stayed the same color blue (new API master test, expiry 2017). I was confused until started to test nitrates and they were steadily climbing. 

I have a piece of malaysian driftwood and it's a freshwater tank.


----------



## MEDHBSI (Sep 4, 2011)

well it takes about 8 weeks or more to cycle, It took my small tank 6 weeks even with help. You can add some seachem stability to kick start the whole thing. The driftwood could be the cause of your ph problem


----------



## crazy72 (Apr 22, 2010)

Very strange that you didn't see nitrites. Usually the first part of the cycle (getting ammonia to be turned into nitrites) is faster than the second part (getting nitrites to be turned into nitrates). How long it takes varies, I think. 3.5 weeks is a little short, but it's not as if you had said one week for instance. If you test kit is new, I would be inclined to think that you can trust it, and if you can, as you said, turn 2ppm of ammonia into nothing but nitrates in 24 hours, you're probably good to go. But I would verify this more than once, with a large water change in between every time to make sure that the pH doesn't crash. Also make sure your water is well oxygenated (e.g. venturi, surface movement).

Keep us posted.


----------



## ryguy76 (Mar 11, 2013)

Ya, it's been surprisingly quick, but I kept the tank well oxygenated and sitting at 80F which should have help speed it up. I've been sitting at zero or close to zero 24 hours after dosing ammo for the last 5 days. Crazy I know, and yes, I wish I saw nitrites as the science doesn't make sense unless it's just getting converted that fast or the test is faulty. but 2ppm of ammo to zero in 24hrs and zero to ~60ppm nitrates is a pretty good indicator that it's doing what it should. I'm going to do a few more WC's to keep the pH from crashing and confirm each time that the ammo and nitrates correlate.

I'll let you know how it goes.

Edit: Just had a thought. I planted some plants a few days ago and have dosed with flourish before and after the 70%WC. is there nitrates in that that could be the majority nitrate source that I'm detecting?

I just ran nitrites again right now, 2hrs after dosing to 2ppm ammo. no nitrites detected.


----------



## hp10BII (Apr 23, 2010)

Do you measure your KH? If you do, what is your reading? IME with a pH crash, that slows down the nitrogen cycle to the point where it may never complete. At this point without any fish, use as much aragonite/crushed coral as you want. It kept my pH levels stable and I was able to complete most of my fishless cycles within 6 weeks.


----------



## ryguy76 (Mar 11, 2013)

hp10BII said:


> Do you measure your KH? If you do, what is your reading? IME with a pH crash, that slows down the nitrogen cycle to the point where it may never complete. At this point without any fish, use as much aragonite/crushed coral as you want. It kept my pH levels stable and I was able to complete most of my fishless cycles within 6 weeks.


No, i don't have a KH test, but is 6.4 considered a pH crash?


----------



## jobber (May 14, 2010)

Is your pH still dropping continuously below 6.4? If so, then yes. If no, then you're pH has stabilized at 6.4.

A crash would be a continuous drop.

Sent from my mobile phone


----------



## crazy72 (Apr 22, 2010)

While I agree that a pH crash will slow down the cycling process, that typically (IME, at least) results in consistently high levels of nitrites if you keep adding ammonia (supposing you are in the second part of the cycle, which I'm certain you are after nearly 4 weeks). In your case, since you don't see nitrites, you have to conclude that either your test kit is defective, or your cycle is finished. The high nitrate reading is an indication of the latter possibility: your cycle is likely finished.

It is probably a good idea to buffer anyway, but I wouldn't worry about the 6.4 pH unless you want to keep Africans or something. I would do a large water change and start stocking.


----------



## crazy72 (Apr 22, 2010)

... and by the way, the reason the pH goes back down is because you keep adding ammonia. If you stop adding ammonia (and even if you add fish, because they'll generate a lot less ammonia than what you're been dropping in there), the pH should stay at whatever it is out of the tap.


----------



## ryguy76 (Mar 11, 2013)

sounds good. I'm going to do at least one more significant WC and start with as close to zero nitrates as i can, dose some more ammonia and and check the nitrates the next day. If I can turn it into nitrates in 24hrs, I'll begin stocking.


----------



## jobber (May 14, 2010)

Water changes are always best. Alternatively, there are bottled live beneficial bacterial that you can use to expedite the cycle only if you want to spend money extra money. Api stress zyme and seachem stabilty are two brands I've used.

You're almost there. Good luck with the rest of the way.

Sent from my mobile phone


----------



## Flear (Dec 8, 2012)

any wood in the tank ?, that can lower PH


----------



## jobber (May 14, 2010)

Flear said:


> any wood in the tank ?, that can lower PH


OP stated there's a piece of malaysian driftwood in the tank in a previous post.

Sent from my mobile phone


----------



## ryguy76 (Mar 11, 2013)

Did another big WC after work today. My Nitrates were between 80ppm and 160ppm. After the WC, they're down to 10 ppm. I had virtually no ammo left from last nights 2ppm dose. It wasn't a full 24hrs, and was reduced to somewhere between 0 and 0.25ppm in less than 20 hours. 

The pH is back to 7.0 again. If tomorrows test yields zip for ammo and a bunch of nitrates, I'm calling it done. I'll do another solid WC to get the excess nitrates out, and then just sprinkle some fish food in until I find fish to stock it with.

Which brings me to my next question. I want 6-7 CPD's, but am having difficultly finding any online. Any ideas where I can get some?


----------

