PH - Ideal, Swing, and should I do something?

TinyChocobo · Mar 15, 2018

Hello!

My 88 gallon DT and 24g sump are swinging between 8.15 during the day and 7.8 at night.

I did build a chaeto reactor which seems to have helped a bit but I think the volume of chaeto to the volume of water is probably too small to make a huge dent.

That said I am running 24/7 lighting on the chaeto - would running it only when the DT lights are off help stop the swings more than 24/7? I figure during the day they may be using up the nutrients so at night there’s not “as much to eat” but I’m just guessing.

I’m running Instant Ocean salt with RO/DI water at 0 PPM TDS according to my meters.

Is this a big enough swing to worry about and is it swinging low enough that I should do something like dose a little baking soda?

Everything in the tank seems fine and if I do need to do anything I will do it slowly over days or weeks.

Mostly just wanting to make sure I’m providing the best environment I can. I’m doing weekly 15% water changes right now.

Lasse · Mar 16, 2018

0.35 swing in pH - little high but not an alarming swing in a well isolated house during wintertime (cold climate). If you want a higher night pH - search for CO scrubber or "use outside air"

Sincerely Lasse

Randy Holmes-Farley · Mar 16, 2018

IMO, the pH swing is not typically the concern, but rather the bottom of it, and a bottom of pH 7.8 is OK.

TinyChocobo · Mar 16, 2018

I recalibrated the PH probe yesterday using fluid I warmed up to tank temperature instead of room temperature and the value went down by 0.05 or so. It got down to 7.76 last night but I suspect it’s no lower than it has been due to the recalibration.

I’m going to open a couple of windows this evening and see if it has any impact.

pluikens · Mar 16, 2018

Found this thread as I'm currently experiencing a similar issue. The noon spikes are when my return pump and skimmer turn off for about 5 minutes during an autofeeder cycle. It's not normal for pH to spike in my sump just because flow through the sump stops, right? The only cause I can think of there is that maybe when flow stops, there's some undissolved soda ash from dosing that raises the pH in the sump water. I don't see any solid soda ash on pumps or heater though. The 8pm spikes are when I dose 2mL soda ash for Alk.

I'm also going to try opening windows but since this isn't really an ongoing solution for Minnesota winters, I would like some people's opinions on CO2 scrubbers. I know that when my pH increases, I'll likely need to adjust my dosing and as CO2 scrubbing media exhausts itself, pH will drop and will need to be swapped out before Alk/Calc demand drops and I overdose. Is there anything else major to watch out for if I decide to add a scrubber?

TinyChocobo · Mar 16, 2018

If opening a window works I’ll put a small hole in the wall and run airline from outside to my skimmer. I’m just going to be opening the windows temporarily to see if PH goes up.

TinyChocobo · Mar 16, 2018

I haven’t changed anything but putting my chaeto reactor on an opposite cycle from my DT lights and upping the flow from 100 to 150 GPH - it looks like the PH drop is much slower today.

FailingUpwards · Mar 16, 2018

Pluikens, you may be coupling signals from your motors. If your cabling is all bunched together, I'd suggest moving them apart and see if you still see the spikes.

TinyChocobo · Mar 16, 2018

My ph started its normal afternoon drop more slowly than normal and then it actually reversed course and started going back up ... I wonder if the flow to my chaeto was just too low and it was eating up too much nutrients on a 24 hour light cycle.

TinyChocobo · Mar 17, 2018

Yeah so far it’s gone up and stayed up.

Randy Holmes-Farley · Mar 17, 2018

pluikens said:
Found this thread as I'm currently experiencing a similar issue. The noon spikes are when my return pump and skimmer turn off for about 5 minutes during an autofeeder cycle. It's not normal for pH to spike in my sump just because flow through the sump stops, right? The only cause I can think of there is that maybe when flow stops, there's some undissolved soda ash from dosing that raises the pH in the sump water. I don't see any solid soda ash on pumps or heater though. The 8pm spikes are when I dose 2mL soda ash for Alk.

I suspect the upward spikes are electrical interference when the pumps stop, not a real pH change. But if you are dosing something at the same time near the pH probe, that would also do it.

TinyChocobo · Mar 17, 2018

I'm not really understanding this. Today it dipped down from 8.02 to 7.71 before starting to climb back up a bit in the middle of the night. ORP was climbing while PH was dropping, and then when ORP started going back down, PH started to go back up...

That said while I understand in theory what ORP is - I'm not sure how ORP and PH correlate if at all... Any advice / explanation is appreciated. I know that @Randy Holmes-Farley definitely knows more about all of this than myself.

At this point I'm just trying to understand this.

TinyChocobo · Mar 17, 2018

From brief research it seems to me that PH decreasing will cause ORP to go up, and vice versa... So perhaps it's the PH itself that's changing and ORP is just changing as a result.

That said I'm still trying to figure this out - it feels like the PH is going up/down at odd times for no real reason that I can seem to figure out.

My LED Lighting on my Chaeto reactor came on at 3PM and my LEDs went off at 11 PM [although they were only 15% intensity and 100% Blue from about 5PM on.

Randy Holmes-Farley · Mar 18, 2018

TinyChocobo said:
I'm not really understanding this. Today it dipped down from 8.02 to 7.71 before starting to climb back up a bit in the middle of the night. ORP was climbing while PH was dropping, and then when ORP started going back down, PH started to go back up...

That said while I understand in theory what ORP is - I'm not sure how ORP and PH correlate if at all... Any advice / explanation is appreciated. I know that @Randy Holmes-Farley definitely knows more about all of this than myself.

At this point I'm just trying to understand this.

The ORP is doing nothing except responding to the pH changes, so just ignore that. ORP depends inversely on pH. Higher pH means lower ORP even when everything else is unchanged.

I discuss that in detail here:

ORP and the Reef Aquarium - Reefkeeping.com
http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm

TinyChocobo · Mar 18, 2018

That’s the conclusion I came to - but I’m still trying to figure out the weird PH changes.

Randy Holmes-Farley · Mar 18, 2018

TinyChocobo said:
That’s the conclusion I came to - but I’m still trying to figure out the weird PH changes.

You are referring to pH changes during the "night?"

pH is the result of many processes, and if you have different day night cycles of lighting in a refugium and main tank, plus possible changes in CO2 levels in the air around the tank based on people coming and going (as well as other things, which might even include wind outside and the air temp outside), the changes may get complicated to interpret.

TinyChocobo · Mar 18, 2018

Randy Holmes-Farley said:
You are referring to pH changes during the "night?"

pH is the result of many processes, and if you have different day night cycles of lighting in a refugium and main tank, plus possible changes in CO2 levels in the air around the tank based on people coming and going (as well as other things, which might even include wind outside and the air temp outside), the changes may get complicated to interpret.

The office is closed up from 5 pm to 9 am every day nobody coming or going.

Algae reactor comes on at 3pm and off at 11 am. Main lighting is on an opposite cycle.

What has me baffled is I can’t seem to correlate the changes to any of the timings.

Randy Holmes-Farley · Mar 18, 2018

TinyChocobo said:
The office is closed up from 5 pm to 9 am every day nobody coming or going.

Algae reactor comes on at 3pm and off at 11 am. Main lighting is on an opposite cycle.

What has me baffled is I can’t seem to correlate the changes to any of the timings.

Changes in air circulation within the building? Might be electrical interference,a s folks have noted.

TinyChocobo · Mar 18, 2018

Randy Holmes-Farley said:
Changes in air circulation within the building? Might be electrical interference,a s folks have noted.

The HVAC fan runs 15 minutes every hour 24 hours a day - beyond the furnace itself running as needed. It’s cold outside - in the 20s Fahrenheit - so it runs periodically.

The sensor lines are all isolated from power. Power runs to the back sensors run to the front in their own isolated paths.