Effect of skimmer on ph

arvind

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I have been using a royal exclusiv vertex alpha 200 skimmer with an outside airline connected to it. My ph used to be in the 7.90-8.15 range. The skimmer pump broke and I replaced it with a red sea 600 skimmer. Now the ph is at 7.65‐7.80. Alk is at 8.12.

My question is, can skimmer have such an impact on ph? Or could there be something else that is affecting the ph in addition to skimmer change?
 

polyppal

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Yeah the fractionation from a skimmer pump could effect the CO2 levels in the tank leading to ph rises or drops
 

arking_mark

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7.65pH is most likely a measurement error.


Your CO2 level around the tank/skimmer would need to be 2100.

SmartSelect_20211020-223140_Pydroid 3.jpg


Long-term exposure to this level would effect your health.

co2-ppm-table.jpg
 

MnFish1

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mdb_talon

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Yes it can definetely have a significant impact. I dont know enough details about those specific skimmers, but if it is bringing in significantly less lower co2 air than the previous skimmer it would not surprise me
 

mdb_talon

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7.65pH is most likely a measurement error.


Your CO2 level around the tank/skimmer would need to be 2100.

SmartSelect_20211020-223140_Pydroid 3.jpg


Long-term exposure to this level would effect your health.

co2-ppm-table.jpg

That chart assumes an efficient gas exhange with the tank and room air which is not always the case.

On another note i personally at one time struggled with PH numbers in the 7.6-7.7 rabge at the lowest part of my swing. The combination of using an oversized reverse lit refugium and outside air to the skimmer i now see lowpoint around 8.1.
 

arking_mark

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That chart assumes an efficient gas exhange with the tank and room air which is not always the case.

On another note i personally at one time struggled with PH numbers in the 7.6-7.7 rabge at the lowest part of my swing. The combination of using an oversized reverse lit refugium and outside air to the skimmer i now see lowpoint around 8.1.

Again. Very unlikely. If you're using an appropriate sized skimmer and powerheads in your tank, your tank aeration is more than adequate. Indoor air quality is usually between 600-1200. pH measurements below 7.8 is not really realistic.
 

arking_mark

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Again. Very unlikely. If you're using an appropriate sized skimmer and powerheads in your tank, your tank aeration is more than adequate. Indoor air quality is usually between 600-1200. pH measurements below 7.8 is not really realistic.

Let me use an analogy. All of us are familiar with temperature. If your tank temp said 40 degrees would you believe it? If you're not feelings really cold in your house, you know that reading has got to be an error.

This is the same for CO2. For a sufficiently aerated tank, a reading below 7.8 is highly unlikely. You personally would notice air quality issues...
 

mdb_talon

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Again. Very unlikely. If you're using an appropriate sized skimmer and powerheads in your tank, your tank aeration is more than adequate. Indoor air quality is usually between 600-1200. pH measurements below 7.8 is not really realistic.

Of course it is realistic and quite possible. In fact the reason why almost all of us have ph swings day to night is because our co2 is not in equilibrium with the air of the room. If it was we would have a pretty much stable PH.

Also if you are going to immediately blame it as an incorrect reading how are you sure that his alk reading is correct? Drop that down to 7.5 and type that in your formula and it changes things as well.

I am certainly not arguing that our PH Probes are completely accurate, but i keep seeing you make this blanket statement and it is simply inaccurate without several disclaimers. Did you ask if he runs a calc reactor. Issues with that can very well spike his co2....though again i stick with the fact that the vast majority of reef tanks simply dont have equilibrium with the co2 level of the air.

In any case none of this is really relevant to the question he was asking anyway lol
 

arking_mark

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Of course it is realistic and quite possible. In fact the reason why almost all of us have ph swings day to night is because our co2 is not in equilibrium with the air of the room. If it was we would have a pretty much stable PH.

Also if you are going to immediately blame it as an incorrect reading how are you sure that his alk reading is correct? Drop that down to 7.5 and type that in your formula and it changes things as well.

I am certainly not arguing that our PH Probes are completely accurate, but i keep seeing you make this blanket statement and it is simply inaccurate without several disclaimers. Did you ask if he runs a calc reactor. Issues with that can very well spike his co2....though again i stick with the fact that the vast majority of reef tanks simply dont have equilibrium with the co2 level of the air.

In any case none of this is really relevant to the question he was asking anyway lol

Most tanks today are adequately aerated via powerheads and skimmers. Most tanks are not supplementing low-pH additives. Most houses are not higher than 1200ppm CO2. There really aren't much else that will lower your pH.

A tank with 7.5 Alk and house air CO2 at 1200ppm will still have a pH above 7.8 NBS. In fact, a tank with 7dKH will be above 7.8 NBS.

SmartSelect_20211021-002938_Pydroid 3.jpg
 

mdb_talon

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Most tanks today are adequately aerated via powerheads and skimmers. Most tanks are not supplementing low-pH additives. Most houses are not higher than 1200ppm CO2. There really aren't much else that will lower your pH.

A tank with 7.5 Alk and house air CO2 at 1200ppm will still have a pH above 7.8 NBS. In fact, a tank with 7dKH will be above 7.8 NBS.

SmartSelect_20211021-002938_Pydroid 3.jpg

Then explain why a tank PH swings .3 to .4 throughout the day?

Again you keep using this false premise that room co2 equalizes with tank co2 when in fact we know this is not the case.
 

arking_mark

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If we set aside the actual pH readings and assume that switching skimmers lowered pH. That would indicate that the tank has increased C02.

This could mean 1 of 2 things:
  1. The tank's aeration has become inadequate which would mean the new skimmer is undersized and existing piwerheads are inadequate.
  2. The skimmer is doing an even better job of equalizing the tank to the higher house CO2 air and countering the pH raising effects of photosynthesis and such.
I'm guessing #2...and that the actual pH us at or above 7.8.
 

mdb_talon

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If we set aside the actual pH readings and assume that switching skimmers lowered pH. That would indicate that the tank has increased C02.

This could mean 1 of 2 things:
  1. The tank's aeration has become inadequate which would mean the new skimmer is undersized and existing piwerheads are inadequate.
  2. The skimmer is doing an even better job of equalizing the tank to the higher house CO2 air and countering the pH raising effects of photosynthesis and such.
I'm guessing #2...and that the actual pH us at or above 7.8.

Unless i misunderstood his skimmer is still hooked to an outside airline which certainly has lower co2 than inside air.
 

arking_mark

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Then explain why a tank PH swings .3 to .4 throughout the day?

Again you keep using this false premise that room co2 equalizes with tank co2 when in fact we know this is not the case.


A tank’s effective CO2 level is determined by CO2 sources (inputs) and sinks (outputs).

The main sources of CO2 are indoor CO2 levels and livestock. The main sinks of CO2 are photosynthetic organisms such as algae.
 

arking_mark

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Unless i misunderstood his skimmer is still hooked to an outside airline which certainly has lower co2 than inside air.

Good catch....then I change my guess to #1...which would pissibly point to aeration issues...and possibly lower than 7.8pH.

In the case, a cup aeration test would discover this.
 

mdb_talon

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A tank’s effective CO2 level is determined by CO2 sources (inputs) and sinks (outputs).

The main sources of CO2 are indoor CO2 levels and livestock. The main sinks of CO2 are photosynthetic organisms such as algae.
Lol now i assume you are just intentionally being obtuse. The entire premise of your argument is that a PH cant be that low because his room co2 would be 2100. However that assumes that the tank co2 is in equilibrium with the room co2.....which again we know is certainly not the case in most tanks because if it was the ph would not swing by .3 to .4 per day for most people.
 

mdb_talon

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Good catch....then I change my guess to #1...which would pissibly point to aeration issues...and possibly lower than 7.8pH.

In the case, a cup aeration test would discover this.
Agree the best way to really know is an outside aeration test and an inside aeration test. Both can also determine to some degree of accuracy(not perfect) how accurate his probe is
 

arking_mark

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Lol now i assume you are just intentionally being obtuse. The entire premise of your argument is that a PH cant be that low because his room co2 would be 2100. However that assumes that the tank co2 is in equilibrium with the room co2.....which again we know is certainly not the case in most tanks because if it was the ph would not swing by .3 to .4 per day for most people.

Please read what I wrote up on tank pH.


In order for your pH to be below air equilibrium, you would have to have inadequate tank aeration or another source that lowers CO2.

The daily tank swings we see are mostly due to the photosynthesis in our tanks that raise the pH.

Your effective pH is the sum of CO2 sources and sinks in your system.
 

mdb_talon

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Please read what I wrote up on tank pH.


In order for your pH to be below air equilibrium, you would have to have inadequate tank aeration or another source that lowers CO2.

The daily tank swings we see are mostly due to the photosynthesis in our tanks that raise the pH.

Your effective pH is the sum of CO2 sources and sinks in your system.

Again this is simple. If a tank was completely aerated(at equilibrium with room air) we would not have ph swings(assuming stable alkalinity). I dont need an explanation of why it is not always at equilibrium as that is my entire point here. Your entire premise(his co2 would have to be 2100) is assuming his tank is at equilibrium.

You are now posting articles that negate your premise by showing that processes within the tank that impact co2 cause ph to go up and down(again precisely because it does not stay at equilibrium)

Or said another way.....it is very possible that processes within his tank have increased co2 levels above what they would be if they were at equilibrium with his room co2.
 
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