Chemical free pH hack

Righteous

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You're correct, he's wrong. How do you explain pearling on plants when the lights are on? That's oxygen being formed during the day. BTW, it's the oxygen level in the tank that leads to higher coral growth, not the PH, which tends to be correlated with O2. I'll reference the scientific literature here shortly.

Pearling is produced in planted tanks when the tank water can no longer keep the O2 being generated by the plants in solution, so it forms bubbles.

Oxygen dissolved in the water (or undissolved when pearling) has no effect on pH.

CO2 dissolved in the tank is what causes pH to drop by generating carbonic acid.

Here's some scientific literature:

 

Randy Holmes-Farley

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I wonder what a CO2 meter would find if placed in a potted plant - I'm guessing the same as the rest of the room since air molecules move at a few hundred meters/sec. ... (although, if you start pulling air from it with a pump intake, that would really remove any concentration difference I'd think.)

Folks have studied the CO2 uptake from plants, and you can see what the effect would be in a small space (1 m^3) from a lot of leaf area (0.5-1 m^2) that is brightly lit (20,000 lux):


Table 1, best result at 25 deg C is ~250 ppm drop in 1 h for 0.5 m^2 leaf area lit.

Scale that up to a normal room size (small to medium room 3 m x 4 m x 2.5 m = 30 m^3) and a normal houseplant down to a normal houseplant lit leaf square footage (say, 0.25 m^2 = 2.7 square feet) , and the effect is quite small. less than 5 ppm drop in an hour.
 

Randy Holmes-Farley

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You're correct, he's wrong. How do you explain pearling on plants when the lights are on? That's oxygen being formed during the day. BTW, it's the oxygen level in the tank that leads to higher coral growth, not the PH, which tends to be correlated with O2. I'll reference the scientific literature here shortly.

I'd be interested to see that if you have a reference, but the effect of lowering or raising pH on coral growth is well studied, and is independent of O2.

It certainly may be true that O2 impacts coral growth, but the pH effect is clear.
 

taricha

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I think the dome idea if it worked, would also starve the plant of the CO2 it needed. Plants that grow underwater have adapted to the CO2 available. I think a terrestrial plant might struggle,

Let's do a very rough mass balance for a plant in a dome plumbed to circulate with the skimmer.

When I feed my tank a couple of generous pinches of flake, it would be about a gram. My fish flake is about half carbon, so I'm inputting about half a gram of carbon.
The plant might add biomass that is 3/4 water (guess) and the remaining mass maybe half carbon. So ballpark, I'd need to grow ~4 grams of plant to offset a generous day of feeding.

Will a house plant do that? Most won't, but some could.
Would the plant in the dome suffer from deprived CO2? Well if it lowered the CO2 in the dome from an ambient level in the house of ~1000 PPM down to outdoor air concentration of 400 PPM, then that would cause a measurable pH change in the tank water, and also still be fine for the plant.

( the issue that would scare me away from this might be that my tank could get low O2 overnight because I have greatly restricted the pool of o2 that can be exchanged with the tank water.)
 

Randy Holmes-Farley

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Let's do a very rough mass balance for a plant in a dome plumbed to circulate with the skimmer.

When I feed my tank a couple of generous pinches of flake, it would be about a gram. My fish flake is about half carbon, so I'm inputting about half a gram of carbon.
The plant might add biomass that is 3/4 water (guess) and the remaining mass maybe half carbon. So ballpark, I'd need to grow ~4 grams of plant to offset a generous day of feeding.

Will a house plant do that? Most won't, but some could.
Would the plant in the dome suffer from deprived CO2? Well if it lowered the CO2 in the dome from an ambient level in the house of ~1000 PPM down to outdoor air concentration of 400 PPM, then that would cause a measurable pH change in the tank water, and also still be fine for the plant.

( the issue that would scare me away from this might be that my tank could get low O2 overnight because I have greatly restricted the pool of o2 that can be exchanged with the tank water.)

The goal is presumably to offset the CO2 in the home air, not only what comes from metabolism of fish food. It's metabolism of human and dog food that's big.
 

Righteous

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I monitor CO2 levels in my house. Here’s a graph of the last couple days.

Periods where you see it drop are when I was actively ventilating the house (open windows, ventilation system running)

With 2 dogs and 2 people working from home it’s hard to keep it down and tends to run past 1000ppm very quickly if I don’t ventilate. No plant can keep up with that level of CO2 generation. (Hence why I run a scrubber)

18E9F4BB-98DE-4A85-8E11-F08FFBAD53EF.png
 

taricha

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The goal is presumably to offset the CO2 in the home air, not only what comes from metabolism of fish food. It's metabolism of human and dog food that's big.

Right. Houseplants are hopeless for that, as threads here have documented.

Hence the hypothetical tweak of plumbing an enclosed plant to skimmer-exchange air with the tank.

(Might be ok for pH, I wouldn't trust it for O2 though)
 

Righteous

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Right. Houseplants are hopeless for that, as threads here have documented.

Hence the hypothetical tweak of plumbing an enclosed plant to skimmer-exchange air with the tank.

(Might be ok for pH, I wouldn't trust it for O2 though)

The problem with the dome is that if it's perfectly air tight, you can't pull air into your skimmer. So the dome would have to have some flow through from room air.

If you do have room air flowing into the plant, its not sealed, and still can't compete with human / dog CO2 production etc.

The best solution is still ventilation, followed by aeration to get to equilibrium. And if that's not enough, a CO2 scrubber, or high pH alkalinity dosing.
 

Randy Holmes-Farley

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Right. Houseplants are hopeless for that, as threads here have documented.

Hence the hypothetical tweak of plumbing an enclosed plant to skimmer-exchange air with the tank.

(Might be ok for pH, I wouldn't trust it for O2 though)

The air flow through the enclosed space to feed a skimmer will mean it never drops especially low if a plant is all that is reducing the CO2.
 

taricha

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The problem with the dome is that if it's perfectly air tight, you can't pull air into your skimmer. So the dome would have to have some flow through from room air.
Plant dome -> skimmer -> plant dome.
The air flow through the enclosed space to feed a skimmer will mean it never drops especially low if a plant is all that is reducing the CO2.
Haha true.
It's a whole lot of trouble to just get air that's basically got CO2 a lot like outdoor air. At that point... just pull in outdoor air instead. :)
 
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emperata

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So in the spirit of science, how about moving the pump away from the plant and seeing what happens. Simple enough.
I have a superlative idea! Let’s just forget it and l accept responsibility for this debacle. After following the forum for so long, l really should have known better. All the best!
 

Righteous

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So this is basically what we’ve been saying

Light calcification rates were greatly enhanced (+178%) by increased seawater pH, but only at normoxia; hyperoxia completely negated this positive effect

In other words increased pH (which is controlled by CO2) increased growth, as long as oxygen is at normal levels. Increasing oxygen past normal levels (hyperoxia) actually negated that effect. So this would suggest pumping O2 in would be detrimental.

Our preliminary results suggest that within the current oxygen and pH range, oxygen has substantial control over coral growth, whereas the role of pH is limited

Their collusion is worded a little strange especially given that they showed increased pH caused 178% increase in growth. I think the point they are making here is that hyperoxia and hypoxia situations can cause serious problems for coral growth in seawater pH ranges. They’re assuming ocean pH levels (they state 7.8-8.7) which don’t get as low as our aquarium levels can, which are kept indoors and have to deal with 1000ppm CO2 or greater.

oxygen level in the tank that leads to higher coral growth, not the PH, which tends to be correlated with O2.

So this study actually directly contradicts that statement. It’s interesting, though, that hypoxia and hyperoxia aren’t that great in this study, so keeping normal levels seems best.
 
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Randy Holmes-Farley

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image.jpg

It says right on the picture that calcification was greatly increased by increased pH at normal O2 levels. Exactly my point. :)

My other concern, certainly, is low O2 and is why I push so hard on O2 even though many folks mistakenly assume their O2 is at saturation.
 

Righteous

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It says right on the picture that calcification was greatly increased by increased pH at normal O2 levels. Exactly my point. :)

My other concern, certainly, is low O2 and is why I push so hard on O2 even though many folks mistakenly assume their O2 is at saturation.

I do find the data that hyperoxia is detrimental interesting. I don’t know of anyone trying to push lots of O2 or how one would even achieve hyperoxia. Could ozone cause hyperoxia via photodissociation?
 
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Randy Holmes-Farley

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I do find the data that hyperoxia is detrimental interesting. I don’t know of anyone trying to push lots of O2 or how one would even achieve hyperoxia. Could ozone cause hyperoxia via photodissociation?

Reef tanks and natural reefs can go hyperoxic during the day and hypooxic at night:

 

Plandauesq

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I live in the south and suffer from two things: a pathological fear of bugs and low pH. Therefore, it’s not possible to flood my apartment with fresh air and my pH was stuck at 8.0. So l put an airstone in my hob and nestled the pump in a dense pothos plant (a super high O2 producer and Co2 scrubber- it’s a type of philodendron that grows like crazy). In two days my pH rose to 8.3.
I have a 300 gallon reef tank with 7.8 pH and desperately trying to raise it. Added CO2bscrubber, which didn’t do much, added kalkstirrer which upped it a tad. Any help here would be much appreciated. Doesn’t the air stones give rise to micro bubbles in your tank?
 
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emperata

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I have a 300 gallon reef tank with 7.8 pH and desperately trying to raise it. Added CO2bscrubber, which didn’t do much, added kalkstirrer which upped it a tad. Any help here would be much appreciated. Doesn’t the air stones give rise to micro bubbles in your tank?
Hi - if you read the thread you saw that some chemists denied my assertion. However, l’m still between 8.1 and 8.3 pretty steadily. To your question: l put the airstone in an hob biowheel with a coarse sponge trickle back into the tank. No bubbles at all in the tank. I truly covet your tank. I have size envy.
 
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emperata

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Hi - if you read the thread you saw that some chemists denied my assertion. However, l’m still between 8.1 and 8.3 pretty steadily. To your question: l put the airstone in an hob biowheel with a coarse sponge trickle back into the tank. No bubbles at all in the tank. I truly covet your tank. I have size envy.
Also, l buffer and add calcium with every water change. All the best, Jeff
 

Plandauesq

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Hi - if you read the thread you saw that some chemists denied my assertion. However, l’m still between 8.1 and 8.3 pretty steadily. To your question: l put the airstone in an hob biowheel with a coarse sponge trickle back into the tank. No bubbles at all in the tank. I truly covet your tank. I have size envy.
Haa!! Thanks.
 
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