PH problems

[reefredy75]

My Ph is at the highest 8.1 and 7.5 at the lowest, but it is highest when the lights are off and lowest when they are on. Is this backwards? I managed to raise it to 8.3 and I left the house for a couple of hours and it was 7.5. Can someone help me with this?
Ca-425
mg-1500
alk 15(high)

[TCU Reefer]

Try dripping kalkwasser. My pH was a little low (7.7) and with a kalk drip, it holds steady at around 8.1.

[The0wn4g3]

I'm no chemistry wiz but I believe the pH should always be higher at night.
Kalkwasser seems to have excellent reviews and that's probably a great solution.
Personally, I use Kent's 2-part solution called "Tech-CB" (parts a & b of course) part A buffers calcium and part B buffers alk and pH, so you can adjust the amount you use to get your desired levels of each. using the suggested dose my pH is 8.1 - 8.3, alk 10-13, calcium 380-420.

[bertoni]

I suspect the problem is measurement error. 7.5 is too low to be real, I think. Are you using a pH meter? If so, the problem might be electrical interference.

[reefredy75]

Yeah, thats why im confused

[bbehring]

what's deemed too high? I'm 8.35 during the day and 8.54 at night.

[bertoni]

8.5 is about as high as I'd let it get, personally.

[reefredy75]

Well I found out it was that I needed to re-calibrate my ph monitor. I woke up this morning and my ph was 3.4!!!!!

[bbehring]

Might be my issue too. I'll look into recalibration.

[Billybeau1]

3.4 :eek2:

You've got a bad probe me thinks. They are only supposed to last 18 to 24 months or so.

Like Jonathan says, could be electrical interference too. Try filling a cup with your tank water and testing it away from the tank. If you still get a bad reading, then the probe is shot.

FWIW, I use the pinpoint pH monitor and clean it regularly. But I do keep an AP pH test kit on hand to keep my probe honest. The AP pH kit is accurate and easy to distinguish color on the chart. Currently my monitor and AP test are right on the money.

Good Luck :)

[WaterKeeper]

<a href=showthread.php?s=&postid=9578807#post9578807 target=_blank>Originally posted</a> by bbehring
I'm 8.35 during the day and 8.54 at night.

That's fine Brent. pH is highest at night, just after lights out ,because the carbon dioxide in the tank has been used all day to produce food (sugars) for the algae. At night they "eat" that food and respire carbon dioxide that makes the pH drop until the lights are on again for awhile.

[bbehring]

Thanks WK. I'll simply watch to make sure it doesn't creep up/down any further than this range. Right now it seems pretty constant in this range, maybe as low as 4.25, since I put the probe in about 2 weeks ago.

[WaterKeeper]

Now that 4.25 could be a problem. :D

[bbehring]

oops ment 8.25, sorry WK. RK2 PH probe.

[preimo]

Now in my tank it seems to drop at night unless i drip.

[bertoni]

[welcome]

That's normal. At night, photosynthesis stops removing CO2 from the water. As the CO2 equilibrates with the ambient air, pH drops.