Sudden pH spike... advice needed.

[olds350racer]

OK, for those of you that have the patience to read this... I need some advice.
Here's my routine for the last few months:
1. 15g of Reef Builder (Sodium Carbonate) added over an 1 hour period each day when the lights go off.
2. 15ml of Reef Complete added mid day every 2-3 days
3. Top off water (~1 gallon/day) with Kalkwasser.
4. 100g magnesium sulfate each week
The results of this routine has resulted in the following over those months.
- A dKH increase from about 6 to 9 dKH
- A more stable pH swing... 7.8-8.0 swings then to 8.0-8.1 swings now
- A magnesium increase from about 900 to 1300
- An increase in Ca from 390 to ~430
And here is where it starts to trouble me. Sunday I was doing a normal dose of Reef Complete when I noticed precipitation. Being that I drip all additives very slow, there was minimal precipitation... so I simply stopped. Monday all was OK (just a little low on the pH... 7.9). Tuesday night I went to fill my doser with Kalkwasser using the same amounts as all the previous nights. Dripped the same drip rate as always, but when I woke up this morning my pH was at 8.4! Not that the value is that bad, but the swing sure is.
Any thoughts as to the problem.
Sorry to be so long winded, but I'm the thinking the events leading to my problem could be the cause.
BTW - 55g, 500w MH 8am-6pm cycle, mixed SPS/LPS/few softies

 

[victor626nj]

have you left any doors open over night or period....also check with someone that has a ph meter to make sure that the probe has not gone bad ...it shouldnt be that old because i only been in this hobby for one year and didnt have it to long before i sold it to you ...but they can go bad ...

 

[cameron]

How are you testing pH?

 

[olds350racer]

Cameron;125679 wrote: How are you testing pH?

Milwaukee pH monitor

 

[olds350racer]

Victor, no doors or windows open. It was too late for me to do anything with this morning, but when I get home I am going to verify against a chemical test.

 

[cameron]

Check the probe and you can always do a big water change say 30%.

 

[olds350racer]

Cameron;125713 wrote: Check the probe and you can always do a big water change say 30%.

The only problem is that my mix is significantly higher than my tank.

Now to the current state....
I just got home and I am showing 8.2. All seems well, so I'm going to let everything naturally balance out. I've never had a swing like this and it worries me that I don't know the reason.

 

[dough]

If your pH probe is in the water like mine it will get coraline aglae build up on the glass bubble and I get a false reading. So every now again I have to clean it off.

 

[kalkbreath]

Just lower your salinity.
A gravity drop of say from 1.025 to 1.021 will reduce your calcium from 420 to about 380 and your alk and pH should drop a point or two as well.
Its interesting that you didn't state your salinity.
Salinity has a huge effect on water chemistry.
Every single element in seawater increases as the h20 content decreases.
There is far less ability to hold calcium and carbonate in suspension when the salinity in up, "white out" happens at even otherwise normal calcium and carbonate levels.

It should always be the first thing you check, not the last.

Many times it is the only parameter out of whack.

 

[kalkbreath]

I have also never met a hydrometer I could trusted.
So even when you think you've got salinity covered double check using another means.

 

[cameron]

olds350racer;125753 wrote: The only problem is that my mix is significantly higher than my tank.

Now to the current state....
I just got home and I am showing 8.2. All seems well, so I'm going to let everything naturally balance out. I've never had a swing like this and it worries me that I don't know the reason.

If your freshly mixed salt water has a pH higher than 8.4, you should probably use a different test kit or check the water you are mixing with.

 

[olds350racer]

Cameron;125926 wrote: If your freshly mixed salt water has a pH higher than 8.4, you should probably use a different test kit or check the water you are mixing with.

Sorry, I guess I wasn't too clear on that one. It is not higher than 8.4... more like 8.3. My thoughts were:
With my pH being closer to 8.0 on a daily basis and a spike to 8.4... the water changes (at 8.3 mix) would not help much with the immediate spike.

 

[olds350racer]

Kalkbreath;125803 wrote: Just lower your salinity.
A gravity drop of say from 1.025 to 1.021 will reduce your calcium from 420 to about 380 and your alk and pH should drop a point or two as well.
Its interesting that you didn't state your salinity.
Salinity has a huge effect on water chemistry.
Every single element in seawater increases as the h20 content decreases.
There is far less ability to hold calcium and carbonate in suspension when the salinity in up, "white out" happens at even otherwise normal calcium and carbonate levels.

It should always be the first thing you check, not the last.

Many times it is the only parameter out of whack.

Even at 1.025 it should not precip at 430ppm and 8 dKH.