Cheap GAC dropping PH??

[MT79]

I noticed a day after changing my GAC and adding a new Poly-Filter that my PH was very low~7.8 after lights on :? Then I saw this comment posted by Steve-S regarding a fish death - "Possible but not the most likely cause unless it also impacted pH which I doubt. That would be more common with carbon ( the kind that bubbles/crackles when water is added) and typically a small tank volume."
I use Aquarium Pharmaceuticals GAC and it bubbles/crackles as described above. Anyone have problems w/ PH and GAC? Any insight/info would be very much appreciated.

 

[steve-s]

Crackling carbon usually indicates trapped CO2/gases. If your dealing with a small water volume, it can negatively impact the pH although rare. The best way to counteract it is soaking the carbon before use in RO/DI until the crackling stops. Also be sure to rinse the carbon afterwards to free any dust and potential of introducing phosphates to the tank.

Cheers
Steve

 

[Bhunsucker]

I've also noticed a drop in my PH with the use of a Poly-Filter in a AC 500 filter in a 55gal tank. Just wondering .....

 

[steve-s]

Never had that issue myself but I did send Bio Marine an e-mail inquiring as to the possibilities and "what ifs". Will post a follow up when they reply.

Cheers
Steve

 

[MT79]

I've always used the same brand GAC, so I'm now thinking it's the Poly-Filter. I don't think a small amount of trapped CO2 (thanks for the info Steve-S) is making that big a difference in a 55gal...
Poly-Filters do mention on the package the possibility of them dropping PH.

Bio Marine an e-mail inquiring as to the possibilities and "what ifs". Will post a follow up when they reply.

That would be great Steve, if they don't respond promptly I'll shoot them an e-mail also.
Today the PH is alittle lower than normal but decent~8.1, I did a small PWC last night. Thanks again guys.

 

[steve-s]

I've always used the same brand GAC, so I'm now thinking it's the Poly-Filter. I don't think a small amount of trapped CO2 (thanks for the info Steve-S) is making that big a difference in a 55gal...
Poly-Filters do mention on the package the possibility of them dropping PH.

I read the package I have and the only area that meantions pH reads...

Polyfilter extends time between water changes. Add water for evaporation loss. If pH shifts below acceptable levels, change water and add new polyfilter.

Definately open to interpretation but the way I read that is if the polyfilter is too old, the increased organics/reduced O2 may cause a shift downwards in pH and a new polyfilter is needed. Moreso an indication that the polyfilter is exhausted.

Bio Marine an e-mail inquiring as to the possibilities and "what ifs". Will post a follow up when they reply.

That would be great Steve, if they don't respond promptly I'll shoot them an e-mail also.
Today the PH is alittle lower than normal but decent~8.1, I did a small PWC last night. Thanks again guys.

I asked...

Can a polyfilter affect pH in any regard when newly added to a saltwater aquarium. I have read where it should help increase overall O2 but was wondering if there could possibly be an initial impact when a new pad is added?

This was their reply....

Poly-Filter (r) may increase the pH level in older saltwater aquaria due to
the sorption of acidic dissolved organic matter and increasing the amount
of dissolved oxygen.

Not a very difinitive reply so I will ask alternate sources...

Cheers
Steve

 

[MT79]

Definately open to interpretation but the way I read that is if the polyfilter is too old, the increased organics/reduced O2 may cause a shift downwards in pH and a new polyfilter is needed. Moreso an indication that the polyfilter is exhausted.
Quote:

Ahh, that would make sense.

Not a very difinitive reply so I will ask alternate sources...

Please let me/us know what you come up with. Feel free to PM me if you want w/ any info. Cheers Steve.

 

[MT79]

Update- I have not saw my purple firefish since a day or two before this PH drop happened. I'm assuming it is dead, I searched around the tank to make sure it did not decide to go carpet surfing(I have a canopy w/ a few small openings). Maybe when the firefish died it caused a bacterial bloom that consumed the O2 and dropped the PH?? I replaced GAC today using the same brand as always and have not seen a PH drop... Either the fish or the poly-filter caused it as far as I can tell. I'm inclined to think it was more likely the fish. Any opinions/comments?
Edit-I should add that the firefish looked alittle beat up before the PH drop, I think from the rogue crab I have not caught yet arrggh. The rest of the fish were and still are fine.

 

[steve-s]

What leads you to believe it was a bacterial bloom?

Cheers
Steve

 

[MT79]

I assumed it was plausible lol...I can not come up w/ anything else. I checked PH again today, after replacing the GAC yesterday, and it was fine. The fish death and Poly-filter are the only other "variables" I can come up w/.

 

[steve-s]

I did some asking around and the only thing of note was the possibility of reduced skimmer efficiencey. Did you notice anything there?

Another point that was made but I first wanted to ask how is your pH monitored?

Cheers
Steve

 

[MT79]

reduced skimmer efficiencey. Did you notice anything there?

No difference noticed there. I clean the cup weekly and had cleaned the pump within the previous 30 days.

Another point that was made but I first wanted to ask how is your pH monitored?

I use just a Seachem test kit. When I added the PH reagent the color of the sample did not change at all.(!) The lowest the scale goes is 7.8 and that's a beige color. A reference test checked out fine as did the results of my QT's PH that day. :?

 

[steve-s]

I use just a Seachem test kit. When I added the PH reagent the color of the sample did not change at all.(!) The lowest the scale goes is 7.8 and that's a beige color. A reference test checked out fine as did the results of my QT's PH that day. :?

So I guess my next question would be what prompted you to check the pH at this particular time and was the pH also tested just prior to adding the pad?

My thought here being if the pH was not tested prior to the addition of the pad, the low pH could have already been pre existing and pads addition was purely coincidental. I don't think you can really be sure until the next time the polyfilter is changed. Test the pH before it's removed and then after the new one is added.

Cheers
Steve

 

[MT79]

what prompted you to check the pH at this particular time

"Things" just did not look right. I did not check PH just prior to adding the Poly-filter. FWIW I've been monitoring it since, and have not had a problem.

I don't think you can really be sure until the next time the polyfilter is changed. Test the pH before it's removed and then after the new one is added

That's what I was thinking too, but I'd hate for the result to be the same. I may try it in my QT after I get the neon goby out. Thanks for the help Steve.

 

[Guest]

It's important to keep in mind that the pH fluctuates naturally during the day and a reading of 7.8 is probably not bad. A significant drop in pH would indicate some water quality issues and would require a further search into the root cause. Think you probably found it with the dead fish. A good water change and you should be fine. If it continues, you might want to point your power heads to the surface to break the water up and allow gas exchange. Replacing tight fitting hoods with eggcrate diffuser will help with gas exchange. Also, during the summer with the windows shut, the CO2 in the air increases a subsequently increases in our tanks as well. This also affects the pH. One way to tell if this is an issue is to aerate some water thoroughly overnight and test the pH. If it's signifcantly different, you have high CO2. Good luck!

KG

 

[cmor1701d]

I have neer noticed a change in pH after changing a poly filter. I keep a pad in the sump for about a month between changes (till it's brown).