PH drop in fishless cycle - please help!!

[katefshaw]

Hi there,

I am currently in the middle of a fishless cycle with my Fluval Edge 23l tank. I am 4 weeks into the cycle and have been following the 'almost complete guide to fishless cycling,' on this forum. It is an unplanted tank and contains bogwood. I plan on keeping red cherry shrimp and have added a heater to the tank, with the temperature currently set at 26 degrees. A couple of days ago my Nitrite and Nitrate readings were off the chart (>5ppm and 160ppm respectively) so I carried out a 50-60% water change. My Ph stayed constant at 7.6ppm for two days after the water change and then drastically dropped today to 6.8ppm. My tap water is very soft and I am aware that this means it lacks sufficient buffers to stabilise ph. The pH of my tap water is 7.4ppm. Should I add crushed coral to my tank and also carry out another pwc?

I am also concerned because I expected my nitrite and ammonia levels to be dropping off as it says in the guide, but my nitrites are remaining sky high even after a water change. They are at 5ppm (or more) and my ammo levels don't seem to be reducing quickly, they are at 2ppm at the minute. What should I do??

My tap water parameters are:
GH 71.6 ppm very soft
KH 35.8ppm
PH 7.4 ppm

Any help would be greatly appreciated!!

 

[cfosgate]

Yes, I would do a PWC and add some crushed coral in a bag to the filter to keep the ph up. At 6.5 ph the nitrification process slows and at 6.0 it stalls and bb start to die. The nitrification process does seriously lower ph during cycling so this is an important item to watch.

 

[katefshaw]

Ok Ill do a pac now then and add some coral. Should I be concerned that nitrite levels are so high towards the end of my cycle? Why aren't they dropping off?

 

[Mebbid]

I don't see a reason to add any crushed coral or honestly even do a water change. The pH of 7.4 is a long way off from the 6.5 you need to worry about. Also, excess nitrites doesn't stall a cycle. You can however drop the ammonia addition down to 2ppm rather than the 4 you've been doing.

 

[Caliban07]

In soft water where kh is low, fishless cycles are always in danger of oh crashes.

The process to convert 1ppm of ammonia to nitrATE uses up 7.14ppm of alkalinity (kh)

If you don't replenish the buffering capacity of the water then ph will fall and the cycle will stop.

You can replenish buffers by changing water, you will have to do this a lot and you will be removing the food for the bacteria.

You can add crushed coral or baking soda to increase kh and keep ph stable.

 

[cfosgate]

Should I be concerned that nitrite levels are so high towards the end of my cycle? Why aren't they dropping off?

Nitrite eating bacteria usually take twice as long to reproduce than the ammonia eating bacteria. They will eventually drop and read zero. It just takes some patience.

 

[katefshaw]

So I've done a pwc and my pH is reading 7.6ppm, Ive ordered some crushed coral and a mesh bag online, was wondering how much do you normally add to the tank. My tanks is 23l?? and then how often do you replenish it to keep things stable?

Thanks for all the help guys

 

[Caliban07]

So I've done a pwc and my pH is reading 7.6ppm, Ive ordered some crushed coral and a mesh bag online, was wondering how much do you normally add to the tank. My tanks is 23l?? and then how often do you replenish it to keep things stable?



Thanks for all the help guys

Just add a couple of handfuls. The calcium and magnesium is good for plants too. It will dissolve when it's done but it takes a while.

 

[katefshaw]

Sorry i keep asking loads of questions but managed to get my ph stable and im concerned that doing a pwc has stalled my cycle. My Nitrite levels have remained at a constant 5ppm before and after my pwc and my nitrate levels seem to be stuck at 80ppm but ammonia is slowly dropping to 1ppm today. Could I have killed off some of the bacteria that convert nitrite to nitrate after the pwc?