My tank yo-yo pH levels

[damsel-in-distress]

Fellow Reefers,

I have a rather interesting thing happening to my tank ever since I began use of the AZ-N03 enzyme treatment on Monday. pH levels started to drop from the usual 8.3 to the high 7s. Overall alkalinity levels hover around 3mg/L and my last check, the calcium level registered 275mg/L. It had been constant around 400mg/L the last few months.

To counteract the low pH and calcium levels, I have been dousing Seachem Reef Builder, Buffer & Calcium Advantage on alternate days, but keeping a careful watch by testing and making sure that nothing is overdosed. I am at wits end cos I can't figure out why the pH has suddenly become so unstable.

The funny thing is pH surges (to around 8.6) when I switch off the filter pump &/or protein skimmer each day for about an hour when I feed DT or zooplankton). Over the period of 6-12 hours, the pH slowly dips to the high 7s again. This has been happening for the last week!

I had a couple of LS casualties b4 the start of the AZ-N03 project.

Can anyone enlighten me what could be causing these pH spikes and dips? There seem to be a direct connection between it and the use or non-use of the filter pump & protein skimmer. Also, I have 4 aeration lines put in temporarily to assist oxygenation of the water while undergoing the denitrating treatment.

Any advice to help understand this situation is appreciated.

[Tanzy]

AzNO3 does consume oxygen and produce carbon dioxide resulting in the decrease in pH. A large pH range for the tank indicates low alkalinity and hence decreased buffering capacity of the water against pH changes.

You should stop AzNO3 and restore alkalinity to 8-10 dKH. The protein skimmer helps with gaseous exchange and helps vent off excess carbon dioxide.

[Infinitereef]

Do a 25% water change to reduce the ph swing.

What happens is that by turning on the filter pump and skimmer, you are putting more oxygen into the tank for the AzNO3 to produce more carbon dioxide.

[Achilles Tang]

I have a rather interesting thing happening to my tank ever since I began use of the AZ-N03 enzyme treatment on Monday.  pH levels started to drop from the usual 8.3 to the high 7s. 

As Tanzy said, the AZ-NO3 enzymes will produce a drop in oxygen as it works to quickly convert the nitrates to nitrogen, affecting PH.

Overall alkalinity levels hover around 3mg/L and my last check, the calcium level registered 275mg/L.  It had been constant around 400mg/L the last few months.

Corals will deplete cal and alk. I doubt if AZ-NO3 has any connection with this.

To counteract the low pH and calcium levels, I have been dousing Seachem Reef Builder, Buffer & Calcium Advantage on alternate days, but keeping a careful watch by testing and making sure that nothing is overdosed.  I am at wits end cos I can't figure out why the pH has suddenly become so unstable.

Fluctuation of PH happens on a daily basis. Mine fluctuates from 7.8 to 8.2 daily.

The funny thing is pH surges (to around 8.6) when I switch off the filter pump &/or protein skimmer each day for about an hour when I feed DT or zooplankton).  Over the period of 6-12 hours, the pH slowly dips to the high 7s again.  This has been happening for the last week!

Have you measured DT's PH? I think it can be quite high.

I had a couple of LS casualties b4 the start of the AZ-N03 project.

Can anyone enlighten me what could be causing these pH spikes and dips?  There seem to be a direct connection between it and the use or non-use of the filter pump & protein skimmer.  Also, I have 4 aeration lines put in temporarily to assist oxygenation of the water while undergoing the denitrating treatment.

PH fluctuates daily, reaching its peak during the 'day' where photosynthesis of algae, microalgae etc consuming CO2 and producing oxygen will boost PH levels. At 'night' when photosynthesis stops and livestock consumes oxygen & produces CO2 that acidifies water... PH drops.

If you have a calcium reactor which uses CO2, it makes PH drops at night even worse.

You can use kalkwasser solution to top up evaporated water at night to help buffer PH as its very alkaline by nature.

After you complete your AZNO3 treatment to drastically reduce nitrates... you can resume normal operations, which is to just keep your cal/alk levels stable.