I’m Stumped..Rapid PH Drop

[PocketGoose]

I’ve been noticing some interesting changes in my system over the last week and was curious if anybody here could shine some light on this situation.

Roughly two weeks ago I started to to see some cyano showing up here and there..no big deal..I was basting and siphoning out when I had the time. I’m referencing this because this is the only thing that has really changed that I was aware of.

Three days ago I was running my normal tests and noticed my PO4 and NO3 had both bottomed out to 0, triple checked with my hanna and salifert kits respectively. I have been running at approximately .1 PO4 and 10-20 NO3 for quite some time, including the prior testing iteration three days earlier. I’m assuming the almost immediate drop is from the recent cyano outbreak and overall imbalance that my system is experiencing right now.

This is all old news to me, I’ve dealt with it in the past like we all do.

Here’s where things get weird. I check my alkalinity daily and noticed it had jumped a whole point to roughly 9.6 from 8.5 - this also sort of made sense to me (I’m probably off here) but I thought I had read that the consumption of nutrients can sometimes lead to an increase in alkalinity, specifically nitrate.

Here’s the part that’s blowing my mind. Since noticing the fallout in nutrients and change in alk, my pH has absolutely fallen off the map. I generally see 8.05 (daytime) 7.8(night). Over the last three days my daily high has been 7.8 and 7.55 on the low end at night. I recalibrated my apex probe today to verify that the numbers were at least relatively accurate..ambient CO2 levels have stayed with their normal levels range (based of my CO2 monitor).

Mag:1350
CA: 525

System is roughly 9 months old.

I dose 150mL of kalk daily to supplement consumption.


Any explanations for the pH dump?

 

[davidcalgary29]

What's your SG trend? Do you have an auto top-off, and is it perhaps dumping fresh water into your system?

 

[PocketGoose]

What's your SG trend? Do you have an auto top-off, and is it perhaps dumping fresh water into your system?

Sits pretty consistently at 1.025. I check almost daily, refractometer was calibrated last week.

I do use an ATO.

That’s a good point though, I’ll reverify after work.

 

[Dburr1014]

How old is the probe?

Post 2 in this thread is RHF.
He goes in detail with his article.

Thread 'What is the correlation between alkalinity and pH?' https://www.reef2reef.com/threads/what-is-the-correlation-between-alkalinity-and-ph.340695/

 

[PocketGoose]

How old is the probe?

Post 2 in this thread is RHF.
He goes in detail with his article.

Thread 'What is the correlation between alkalinity and pH?' https://www.reef2reef.com/threads/what-is-the-correlation-between-alkalinity-and-ph.340695/

Less than a year old. It was reading almost spot on with the calibration fluid.

I’ll check it out, thank you!

I’m wondering if there’s any correlation with the cyano and oxygen consumption..causing pH to spike down.

 

[Reef-_-Noob]

I've used chemipure and registered a PH drop from 8.2 to below 7.8 tested at same time consistently. Not sure if it was the product itself or chemical balances affected. Nobody here was much help they kept telling me to test at the same time lol

 

[Court_Appointed_Hypeman]

I have had 2 sudden PH crashes, one was right before a bacterial bloom and roughly 2 weeks into lyngbya appearing in my sump. The other was just after dinos appeared, both events were preceeded with 0 nutrients.

I think photosynthetic activity drops with the low nutrients causing less resperation, but it might also be something else caused by bacteria/archae

 

[PocketGoose]

I've used chemipure and registered a PH drop from 8.2 to below 7.8 tested at same time consistently. Not sure if it was the product itself or chemical balances affected. Nobody here was much help they kept telling me to test at the same time lol

That’s interesting, makes sense. I don’t have any chemical filtration in place currently, I will occasionally run carbon.

I have had 2 sudden PH crashes, one was right before a bacterial bloom and roughly 2 weeks into lyngbya appearing in my sump. The other was just after dinos appeared, both events were preceeded with 0 nutrients.

I think photosynthetic activity drops with the low nutrients causing less resperation, but it might also be something else caused by bacteria/archae

This sounds exactly like my scenario. There could be some Dino’s in the mix too but all I’m seeing currently is the cyano. What was your plan of action like? I’ve suspended the use of my skimmer and have been feeding the corals more often along with adding some neophos/neonitro to try and get the nutrients off the floor. Hoping I can maintain relative health of the system until things start to rebalance.

I guess my over arching question is how these processes happen and why.

 

[Pod_01]

This is all old news to me, I’ve dealt with it in the past like we all do.

I been doing this for 6+ years and I never had NO3 go from 20-30 down to zero in 3 days. Also I did not have PO4 go from 0.1 to zero in 3 days. PO4 alone tends to be bound in rock etc… and will leach out. Reading the description it sounds like this happened while the tank was just sitting there,

I suspect you are leaving out some details that might help to explain what is happening.

Have you been dosing NO3 or PO4 and stopped? Other similar products?
Maybe picture of the tank in white light might help.

In general reef tank wants to have stable Ph range and they tend to settle in, bouncing around indicates something is off.

At a glance you Calc is elevated, I prefer value of 425. Alone this might be ok, but with other parameters being off…

I personally never had luck with Kalk, I do understand some like it a lot but I honestly I think this method is for advanced reefers, just my opinion.

 

[exnisstech]

I personally never had luck with Kalk, I do understand some like it a lot but I honestly I think this method is for advanced reefers,

I love kalk. I use it in my largest system to help stabilize calcium and alk and reduce the amount of 2part needed. But for me it has zero effect on pH. I drip kalk 24/7 (1200ml daily) in my 180g and whenever I test pH all 3 of my tank have the exact same pH and the other two get 2part only no kalk. How people get pH boosts out of kalk has remained a total mystery to me

 

[jda]

Photosynthteic bump in many tanks is around .2 on the pH scale. Folks can also have pH drop rapidly this time of year as co2 in their homes climb without introducing fresh air and letting high co2 air escape. indoor co2 of 400-500 is great but in my house it can climb to 700-800 and the tank is still OK but then the pH quickly starts to drop if the co2 climbs more.

Rock and sand buffer po4. Unless you are using a strong po4 removal media like GFO or LC, there is little chance that you went from .1 to nothing so quickly - you would have had to remove all of the po4 bound to the rocks and sand.

no3 can suddenly drop as sandbeds develop anoxic zones that turn no3 into N gas and complete the nitrogen cycle. These can be sudden.

 

[Pod_01]

no3 can suddenly drop as sandbeds develop anoxic zones that turn no3 into N gas and complete the nitrogen cycle. These can be sudden.

jda so out of curiosity for this to happen do you need certain depths of sand or any will do?
I don’t question that this cannot happen I am curious about the conditions required for it to happen?

I have not seen it (sudden drop) but I had sand goby for long time (till it decided to carpet surf) and my sand is on the thin side. On the flip side my NO3 has been below the 1ppm for 2 years so perhaps I do have it…. My NO3 declined over months.

 

[jda]

I put in 3 inches of sand, but is is now 2-4 inches with the cucumbers and other critters going to work over the years. My nitrate is constantly about .1, or so. I would not matter if I constantly dumped in sodium nitrate, the bacteria would chew it all up and I would be at .1 again in no time.

Any depth can work, but deeper is more efficient. Even a small bit of sand under rocks and stuff can become anoxic.

 

[Randy Holmes-Farley]

The reduced pH will reduce demand for alk, and if you kept dosing the same amount of alk, it would rise.

Lowering nitrate also boost alk a little bit.

If nutrients are low enough, it might reduce photosynthesis and thus lower the pH by reducing the CO2 consumption.

 

[PocketGoose]

All very interesting thoughts here.

To answer the question of missing information, I was not dosing nitrates or phosphates into the system prior to the crash. I’m sure there is PO4/NO3 in the system but my hanna just isn’t picking it up. I’m telling you all though, within three days it dropped to 0. Tank was a dry start so maybe the rocks are still reaching saturation. Tank is only 9 months old.

I agree with you Randy regarding the alk and I have adjusted my dosing routine to account for a larger swing in alk.

As for my sand bed it’s probably sitting at .75 inches if that, not much.

House has been aired out daily with little change in pH. I have been doing this since the weather has started to cool in Florida and noticed an increase in pH prior to the current situation.

 

[PocketGoose]

Here is the graph, you can see the the high a few days ago from opening the windows. Three days later I can’t get it above 7.8 with the same ambient CO2 levels in the house. That number peaks at about 1300-1400 but the last few months I would rarely see it dip below 7.7 with the aforementioned levels. This graph is proof that something changed rapidly, correlating with the decline in nutrients.

 

[jda]

Your co2 levels are at 1300-1400? If so, if you get those to 400-600, I think that most of the pH issues will go away.

Your probe could also be losing calibration or needs replaced. They tend to drift for no reason when this happens.

 

[PocketGoose]

Your co2 levels are at 1300-1400? If so, if you get those to 400-600, I think that most of the pH issues will go away.

Your probe could also be losing calibration or needs replaced. They tend to drift for no reason when this happens.

Unfortunately it is not feasible with two kids two dogs and the summer in Florida to lower ambient CO2 levels like I mentioned earlier, these numbers are on par with what I’ve seen all summer but the pH would reach daily highs of at least 8.

 

[jda]

Before you decide that it is not feasible, you should at least read about what co2 levels like that can do to cognitive abilities and child development. You may or may not find the research compelling, but it is worth a read to determine for yourself. Even if you end up being 50/50, a few dollars a month to cool air brought in by a few minutes of fresh air every day might be cheap insurance against the well being of humans and pets. Anyway, I will bow out...