Can't Get My Alk up?

[hollback]

I have been dosing Randy's 2 part for about 8 months now. All of a sudden I have been having weird percipitaion and I can't get my Alk over 6.7 dKH. Ca is at 420 normally. I drip in my Alk of the 2-part but I never get the snow parcipitation. A few hours later I get a white film on my glass instead. It seems like something is limiting my Alk from rising. I dosed epsom salt hoping that magnesium was keeping the Alk from rising but this didn't help at all. What am I missing?

 

[Randy Holmes-Farley]

Have you measured the magnesium?

How high does the pH get by the end of the light cycle?

 

[hollback]

Wow! I didn't expect such a quick response. I checked my pH after my lights went out and it was at 7.7-7.8! I don't have a magnesium test kit but I am going to have it tested at our club meeting on Friday. I assume that my pH should be higher. Is this why I can't raise my Alk?

 

[steve the plumb]

You should get a mag test kit.Its not a test that you will need to do often but once a month is fine.I have a low ph and alk is at 9 dkh.How sure are you of your cal levels?My cal is at 440 ppm.I use a doser for randys formula.Have you mixed a new batch and maybe didn't make it as strong.The ph shouldn't affect your alk dosing, more than often ph goes up when dosing the alk(baking soda mixed with ro) vs going down I have yet to see my ph go dwn when adding the alk.Have you always dosed the same amount.Did you try to increase dosage.

 

[Randy Holmes-Farley]

Is this why I can't raise my Alk?

No. Low pH actually makes it easier to maintain alkalinity. How are you measuring pH?

 

[hollback]

I use Salifert kits and this Milwaukee pH monitor. I had my LFS test my Ca with a Salifert kit and they said I was at 470. If I lay off Ca addition and just add Alk suppliments will this bring up my dKH? I'm having my Mag tested tomorrow. Thanks for your help!

 

[bertoni]

Skipping the Ca supplementation sounds like the right idea. Adding alkalinity supplements will likely bring up dKH, but you might see precipitation if the Mg is far out of line.

 

[hollback]

Thanks guys, you've been very helpful. :thumbsup:

 

[bertoni]

Good luck!