Sudden drop in PH and Alk!

[SimplyVibing]

Will attach parameters from a water test taken 10 minutes ago and one from a couple weeks ago.

Only effects in the tank is moderate bleaching in a montipora. Yesterday I did a 20% water change, same business as usual. I used the same salt as always (instant ocean for reefs) and same RODI water.

The only thing I can think of is that my tank was recently fallow for 76 days (for ich eradication) and my fish were just added back in— only a medium ocellaris clown, small Valentini puffer, and a full grown mandarin dragonette. The tank is 50 gals.

Any ideas what the heck could have caused this PH/alk drop? And how to correct it? Thanks in advance!!!!

 

[Phycodurus]

12.5 dKH is on the high side (and ultimately wastes calcium). you can nudge it lower gradually with additional water changes. (are you using lime water?)

the lower pH may be related to poor air circulation in the room. try opening a nearby window and testing pH a couple of hours later.

 

[SimplyVibing]

12.5 dKH is on the high side (and ultimately wastes calcium). you can nudge it lower gradually with additional water changes. (are you using lime water?)

the lower pH may be related to poor air circulation in the room. try opening a nearby window and testing pH a couple of hours later.

Hi there! 12.5 dKH was the reading a couple weeks ago, now it’s at 6ish (the big drop is why I’m concerned). The area the tank is in has good air flow: the room is open and has a fan, the tank is uncovered, the door a few feet from the tank is open a few hours a day. It is in direct sunlight though, could that affect the ph?

 

[Crustaceon]

I’m seeing a sharp drop in nitrates and phosphates which first tells me you likely had a bacteria bloom which isn’t always visible. The second thing that points me in this direction is that this can also have an impact on ph which also happens to act as buffer for alkalinity. Carbon dosing? Maybe Nopox?

 

[SimplyVibing]

I’m seeing a sharp drop in nitrates and phosphates which first tells me you likely had a bacteria bloom which isn’t always visible. The second thing that points me in this direction is that this can also have an impact on ph which also happens to act as buffer for alkalinity. Carbon dosing? Maybe Nopox?

Thanks for the help! I’ll definitely add some carbon tomorrow morning.

 

[NewGoby]

To be honest, I'm not sure why you're surprised, these readings are 3 weeks apart, and your tank used up some of the alkalinity, which is completely normal.. I test alkalinity 2x per week, and I dose .65 points of alkalinity a day, because that's what my tank uses.

The change in ph could be explained if your tank is in a closed off room, that's not frequently ventilated, an increase in carbon dioxide in the air will lower your PH - but you mentioned that it's in a well ventilated room - you could always add a co2 scrubber - just to remove any additional co2.

Also could be what @Crustaceon said

 

[SimplyVibing]

To be honest, I'm not sure why you're surprised, these readings are 3 weeks apart, and your tank used up some of the alkalinity, which is completely normal.. I test alkalinity 2x per week, and I dose .65 points of alkalinity a day, because that's what my tank uses.

The change in ph could be explained if your tank is in a closed off room, that's not frequently ventilated, an increase in carbon dioxide in the air will lower your PH - but you mentioned that it's in a well ventilated room - you could always add a co2 scrubber - just to remove any additional co2.

Also could be what @Crustaceon said

Oh okay, thank you! The reason why I’m concerned is because it’s never done this before, and the tank is about two years old. My alk has been 12 dKH for years now lol. Thanks again for your advice!

 

[NewGoby]

Oh okay, thank you! The reason why I’m concerned is because it’s never done this before, and the tank is about two years old. My alk has been 12 dKH for years now lol. Thanks again for your advice!

Ofcourse, no problem - your corals (basically any except soft-corals) will use alkalinity in combination with calcium - a sharp rise in calcium will also make your alkalinity drop, and a sharp rise in alkalinity will make your calcium drop.

12.0 is generally on the high side of the spectrum, anywhere between 8 and 12 is usually adviced.

Maybe the water you've been using to refill any evaporation has had a high alkalinity - which recently could've changed?

I'm from the Netherlands - and I used to refill my tank with tap water - because the parameters over here used to match up amazingly well - but recently the calcium & alkalinity in my tap water have risen by such a large amount that i'm now using RODI water instead.

If you have any other questions hit me up - my dms are always open

 

[SimplyVibing]

Ofcourse, no problem - your corals (basically any except soft-corals) will use alkalinity in combination with calcium - a sharp rise in calcium will also make your alkalinity drop, and a sharp rise in alkalinity will make your calcium drop.

12.0 is generally on the high side of the spectrum, anywhere between 8 and 12 is usually adviced.

Maybe the water you've been using to refill any evaporation has had a high alkalinity - which recently could've changed?

I'm from the Netherlands - and I used to refill my tank with tap water - because the parameters over here used to match up amazingly well - but recently the calcium & alkalinity in my tap water have risen by such a large amount that i'm now using RODI water instead.

If you have any other questions hit me up - my dms are always open

Thank you so much for all of the helpful info! I’ve always used RODI for everything in my tank, so I’m puzzled as to how/why the alk changed. Although I have recently added more SPS, so that could be a culprit.

Just dosed alk for the first time this evening! You’d think I would have done that by now— my reef has been running for almost 2 year now lol

SUPER jealous that your water is so clean where you live!

 

[NewGoby]

Thank you so much for all of the helpful info! I’ve always used RODI for everything in my tank, so I’m puzzled as to how/why the alk changed. Although I have recently added more SPS, so that could be a culprit.

Just dosed alk for the first time this evening! You’d think I would have done that by now— my reef has been running for almost 2 year now lol

SUPER jealous that your water is so clean where you live!

Yeah it's great! Have you changed the filter in your RODI machine recently? If not - wear on the filter (or scrubber - whatever you want to call it) might cause it to work less efficiently

I don't have an RODI machine myself - it's cheaper for my to just buy the water, so I'm not sure how to check if the filter on the RODI machine has been worn out - perhaps someone else could chime in on that?

I personally use the Hanna Alkalinity, Calcium & Po4 checkers - because they're super accurate & I always have trouble reading colour charts haha ^^