ph keeps dropping during cycling

[Ariel Scott]

Hello All,

   So I started cycling my system about 2.5 weeks ago using Ammonium Chloride.  My initial readings after adding the ammonia were as follows:

ph - 7.4 ammonia - 3.8 nitrites 0 and nitrates 0. 

Within four days my nitrites rose to 1.8 and my ph was steady around 7.3. Within another 3-4 days nitrates were around 8.5 ( I don't know if this was completely accurate as I later found out I was doing the test wrong).   Everything seemed like it was going fine until about 8 - 10 days in and my ph dropped to 6.0 and the nitrites and nitrates steadily dropped until they were both 0.  

I began adding hydrated lime in small amounts and was able to get the ph back up to around 7 which also caused the nitrites to come back.  However, within a day or two the ph dropped back down 6.  I have continued to add hyrdated lime everyday but its seems I can't keep the ph up for more then 24 hours before it drops.  The nitrites also seem to drop whenever the ph drops. 

 I'm not sure what I should do at this point.  Should I keep adding lime or do a water change?  I have only done about a 5-10% water change throughout the process.  Any help would be greatly appreciated.

Ari

[Verna Gross]

I'm also a newbie but when this happened to us we did a 30% h2o change as our source h20 has a pH of >8. I also added potash all was well within a couple days and has stayed well

[Harold Sukhbir]

Hi Ariel,

How big is you system(volume of FT and GB) and how much lime are you, did you add?

[Ariel Scott]

My system is a 35 gallon FT and same for the grow bed. I usually add around 1/2 - 3/4 teaspoons of lime.  This usually brings the ph back up around 7.0 to 7.4 but like I said it drops back to 6.0 within a few days

[Harold Sukhbir]

Hi Ariel,

One more question.......... what is your source water? Where did you get it?

[Vlad Jovanovic]

I bet Ariel has soft aggressive, un-buffered water...Or perhaps is using rain water of RO water...Hopefully she'll clue us in...

At any rate, I'd forgo the hydroxides (lime) for now, and jack my kH to well over 150-150 with some sort of bicarbonate...Sit back and let cycling commence...and while I was doing that I'd hang a bag of shell grit (calcium carbonate) somewhere in the system for later...

[Harold Sukhbir]

Hi Vlad,

Ditto.................

Vlad Jovanovic said:

I bet Ariel has soft aggressive, un-buffered water...Or perhaps is using rain water of RO water...Hopefully she'll clue us in...

At any rate, I'd forgo the hydroxides (lime) for now, and jack my kH to well over 150-150 with some sort of bicarbonate...Sit back and let cycling commence...and while I was doing that I'd hang a bag of shell grit (calcium carbonate) somewhere in the system for later...

[Ariel Scott]

I am running the system in my apartment and using Denver City tap water.  Our faucet has a pretty cheap filter mounted on it which I think removes some fluoride.

[Harold Sukhbir]

Hi Ariel,

I think Vald is right about you source water. Somehow it may come stripped of the carbonates from source. I normally do exactly what Verna suggested and add potash(potassium hydroxide) together with the lime(50/50). After a few applications the situation usually normalizes to a point where i only have to dose weekly/biweekly.

[Ariel Scott]

Ok I looked around on amazon and found a few different options.  Any recommendations between these three or are they essentially the same thing:

Potassium Hydroxide Flakes

Potassium Hydroxide Devil Flakes

Espoma Potash Bag

Thanks.

[Harold Sukhbir]

Hi Ariel,

I am aware that the Devil product is supposed to be food grade, so this may be a good option for you. They are also available in pellet form, but there is no difference if you're using the flakes. I don't have any information on the other two items on your list so i cannot comment on them.

[Ariel Scott]

I got the potash but it looks like the system has balanced out without it.  PH seems to be stable around 6.8

[Harold Sukhbir]

Hi Ariel,

Great! Please keep and eye on the PH fairly regularly (2x weekly), as/when it starts dropping you should add small equal amounts of potash and lime.