Why water change day seems to grow aquatic plants better

Tom Barr

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Solcielo lawrencia;115235 said:
If I were to do multiple WC's a day, when would I fertilizer?

Do water changes with 100% RO or distilled water also cause plants to grow faster?

Oxygen and Air Nanobubble Water Solution Promote the Growth of Plants, Fishes, and Mice
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065339

Right after you do the water change, you add the ferts, or during the refill.
Yes, the RO water changes I've done for clients do have a similar effect.
 

Tom Barr

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The article states they got 30+ ppm of O2.
This should be extremely toxic to plant and animal life FYI.

Typical water had 7.7 ppm.

Dissolved ranges at 200% or in this case, about 15 ppm, is highly inhibitory to algae and aquatic livestock.
400% would be, of course, very lethal.

The O2 ppm was about 8.5-9.0 ppm in the plant test for some reason.
I'm not clear and why that was........or was not.

That difference I do accept in helping growth a little bit.
But it may be due to the disturbance of the boundary layers and have little to do with the O2 ppm levels themselves. They did not control for that.
Any plant science reviewer would nail them on that issue.

The notion that a slightly higher O2 will enhance respiration, thus growth, under ideal conditions is well founded and not new, the ability of nano bubbles to maintain a slightly higher ppm of O2 is possible.

So are wet/dry filters better for aquariums since the O2 is higher? what does that imply? Is adding more O2 the key and why we can add more CO2 with higher O2? Again, this is something aquarist using CO2 have found.

Seems to agree with the paper.
 
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Tom Barr;115244 said:
The O2 ppm was about 8.5-9.0 ppm in the plant test for some reason.
I'm not clear and why that was........or was not.

Perhaps that is because it was grown hydroponically and the water is more saturated with O2 than normal.
 
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The change in osmotic pressure is what's causing the immediate pearling while adding fresh water. I first noticed this when I mistakenly added too much CaSO4 and MgSO4 to the tap water weeks prior and no pearling took place as it usually does. Yesterday, I did a 90% WC and added less GH and noticed it pearled a bit more. Then today, I did another 90% WC and didn't add any GH and it was pearling even more. All of these recent WC were done at night, 8pm, without any direct light source. I'm pretty certain I can induce pearling in complete darkness so that the gas escaping from the plants is not the direct result of photosynthesis.

So can the change in osmotic pressure be the cause of the increased plant growth?
Can others confirm that it's osmotic pressure by varying the amount of GH to the fresh water during a WC?
 

Matt F.

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I used to get bubbles on the inside of my acrylic aquarium walls after a water change. I also get bubble on the inside of my glass tank walls, too. I believe the same thing is happening with the plant leaves post water change, but I'm not that kind of a science guy, so I'll have to wait till someone chimes in regarding the osmotic pressure hypothesis. Observation clearly shows that when you add O2 rich water, you tend to get bubbles.
 

Yo-han

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Solcielo lawrencia;115675 said:
The change in osmotic pressure is what's causing the immediate pearling while adding fresh water. I first noticed this when I mistakenly added too much CaSO4 and MgSO4 to the tap water weeks prior and no pearling took place as it usually does. Yesterday, I did a 90% WC and added less GH and noticed it pearled a bit more. Then today, I did another 90% WC and didn't add any GH and it was pearling even more. All of these recent WC were done at night, 8pm, without any direct light source. I'm pretty certain I can induce pearling in complete darkness so that the gas escaping from the plants is not the direct result of photosynthesis.

So can the change in osmotic pressure be the cause of the increased plant growth?
Can others confirm that it's osmotic pressure by varying the amount of GH to the fresh water during a WC?

This immediate pearling has nothing to do with plant growth!! After a water change even the glass pearls, is it producing O2? No! This is also referred to as false pearling. It's just that cold water holds more gasses and after changing the water it gets warmer and can't hold all those gasses. This is why you get it without light as well. Whether the osmotic pressure has anything to do with it I don't know, but temperature certainly does. But this phenomenon has little to do with plant growth. Real pearling is not a simple reflection of healthy growth. With enough flow you can have the most healthy growth but no pearling. Myself, I've only pearling in the corners (slow water movement) on fast growing plants and inside the substrate (pearling from the roots).

But it's not really on-topic. Why do plants grow better after a water change? I gave it a thought the last few weeks and I think maybe it has something to do with electrons. Ions like magnesium and calcium tend to lose electrons to cells under oxidation. When doing an water change you renew the positively charged ions. Just a thought though!
 

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Remember that aquatic plant leaves are like sponges, they are filled when submersed continuously, but when exposed to air, then re submerged again, they hold a lot of gas from the air.
We see a lot of this false pearling due to this and the gas being released due to temp increases from the tap(I'd say the lion's share).

We need to look at the longer term growth from doing more/frequent water changes, and perhaps algae reduction etc.
 
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Yo-han;115681 said:
This immediate pearling has nothing to do with plant growth!! After a water change even the glass pearls, is it producing O2? No! This is also referred to as false pearling. It's just that cold water holds more gasses and after changing the water it gets warmer and can't hold all those gasses. This is why you get it without light as well. Whether the osmotic pressure has anything to do with it I don't know, but temperature certainly does. But this phenomenon has little to do with plant growth. Real pearling is not a simple reflection of healthy growth. With enough flow you can have the most healthy growth but no pearling. Myself, I've only pearling in the corners (slow water movement) on fast growing plants and inside the substrate (pearling from the roots).

I wasn't talking about pearling. (The gas is clearly coming from the plants as I can see it form into large drops, btw.) I was talking about the change in osmotic pressure. The plants are probably able to sense the change in osmotic pressure and maybe open up the pores making the cells more permeable to nutrients. WCs may the be time with the most rapid change in tonicity and the plants respond to it which results in increased growth.

I don't know enough about plant cell walls but do they respond like cell membranes in which hypotonic solutions cause cells to lyse and a hypertonic solutions causes it to crenate?
 

Matt F.

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The gas may be coming from the plants, but the water surrounding it is also at its max saturation point, so that's why you'd see a bubble around the leaves. This is mostly because of the replacement water being oxygenated. I get bubbles on my Eleocharis Belem and it never touches the surface of the water. I get this with the lights on or off. It's always immersed even during my >80% biweekly water changes. At the same time I get bubbles (O2) on my aquarium walls, the lily pipes, and the eheim skim350 post water change. I think it would be almost impossible to measure how much respiration the leaves do post water change by sight alone. Are you measuring the gas in some way to support your assumption?
 
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Yes, cut stems of Rotala have gas escaping from the cut ends. Dissolved gas from the water will not be entering the stems just to outgas as the rate I'm seeing. The same goes for HC. It's not dissolved gasses from the water forming gas bubbles on the plants. It's from the plants, themselves. This is why adding or not adding GH to the fresh water can result in the change in pearling rates.
 

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There is a difference between pearling and streaming. Initially you were talking about pearling after a water change. Now you are talking about streaming. All plants stream assuming they are actively photosynthesizing. This happens whenever you trim aquatic plants. Nothing new or amazing here. I'm getting a bit confused about what we are talking about. I think generally speaking Yo-Han is correct when he states that pearling is not an accurate representation of true aquatic plant health or growth. You have to look at the overall picture, not just one aspect of plant health. Some plants peal like crazy, others don't as much.

I don't think pearling or perceived pearling is indicative of anything other than introducing O2 rich water with a water change. Maybe something else is going on that we are missing. Maybe it's a combo of things. To reduce what we see in tanks that get frequent water changes to just one factor would be foolish. Many things physiologically are going on I would assume (if I remember my animal and plant diversity course...lol).
 
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Tom Barr

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Solcielo lawrencia;115690 said:
I wasn't talking about pearling. (The gas is clearly coming from the plants as I can see it form into large drops, btw.) I was talking about the change in osmotic pressure. The plants are probably able to sense the change in osmotic pressure and maybe open up the pores making the cells more permeable to nutrients. WCs may the be time with the most rapid change in tonicity and the plants respond to it which results in increased growth.

I don't know enough about plant cell walls but do they respond like cell membranes in which hypotonic solutions cause cells to lyse and a hypertonic solutions causes it to crenate?

Pores, meaning Stomata? Most aquatic plant stomata are non functional.

If you go from say a TDS of say 100 to say 300 rapidly, then maybe.
But dosing ferts would accomplish this same thing vs saya water change

Using the fert salts, we can change the osmotic potential outside the plant.
But plants are very good at regulating things endogenous vs exogenous conditions.
You'd have to really push things pretty high to get a significant effect I would think.

Fish will have the same issues, they do not seem to mind.
 

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I think the discussion is good here. There are quite a few possible hypotheses.

We see in tidal systems, that many plants do very well(Sacramento Delta, East Coast of USA, South East Asia, India, Sri Lanka, etc, then marine plant systems have this also worldwide), the flow and emergent/submersed conditions= high productive growth regions.

If the CO2 is off, water changes, frequent ones, seems to offset the issues a great deal, more than anything else I have seen.
 
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There is no difference between pearling and streaming. A string of gas bubbles rising from a plant = a string of pearls = pearling. Gas bubbles coming from a plant but hasn't broken away from the plant to the surface is the same thing. But my inquiry was not about pearling. It was about the change in osmotic pressure. The previous test a few posts back showed zero pearling when removing and adding back the same water. Why? Because the tonicity of the water taken out and added back in was exactly the same. But then adding fresh water caused it to pearl from both the HC and the cut stems of Rotala before I even finished refilling. This, combined with this recent test, confirms (at least to me) that any pearling right after a WC is the result of osmotic pressure. Whether or not the changes in osmotic pressure directly leads to increased plant growth is my inquiry.

This conclusion also puts the variable of pressure back on the table.
 
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Matt F.

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No, there is a difference between streaming and pearling.

Streaming occurs when you break a part of the plant or trim. The gas escapes from the open wound in a stream of bubbles. Sometimes the bubbles come out at 1 bps. Other times it's faster or slower. You see a stream of bubbles from the same origin (a damaged portion of a plant or a freshly cut stem).

Pearling usually denotes the bubble(s) you see at the tip of an uncut leaf, root, or stem (produced internally by photosynthesis). For pearling to be true, it should happen without the aid of a water change. Water change induced bubbles are not the same as pearling. Water induced bubbles show that the newly introduced water is O2 saturated. Nothing more.

All your findings show is that when you introduce the same water into the tank, the O2 levels are the same = no pearling.
When you add new water, the newer water has more O2 = "pearling" (although it's not true pearling).

What was your water source for the newly introduced water?

I would also venture to guess that water with fewer organic pollutants will be richer in O2 than stale tank water that is a few days old and has been recirculated a few thousand times in a closed loop canister filter system.

You're going to have to try harder to convince me about this osmotic pressure = plant growth hypothesis (remember that you haven't proven anything, you're made an empirical observation). Just because something appears to be so doesn't mean one can assume w/o doubt that the idea is right. Did you control for all variables in your study?


Solcielo lawrencia;115715 said:
There is no difference between pearling and streaming. A string of gas bubbles rising from a plant = a string of pearls = pearling. Gas bubbles coming from a plant but hasn't broken away from the plant to the surface is the same thing. But my inquiry was not about pearling. It was about the change in osmotic pressure. The previous test a few posts back showed zero pearling when removing and adding back the same water. Why? Because the tonicity of the water taken out and added back in was exactly the same. But then adding fresh water caused it to pearl from both the HC and the cut stems of Rotala before I even finished refilling. This, combined with this recent test, confirms (at least to me) that any pearling right after a WC is the result of osmotic pressure. Whether or not the changes in osmotic pressure directly leads to increased plant growth is my inquiry.

This conclusion also puts the variable of pressure back on the table.
 
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Matt F.

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This makes sense to me.


Tom Barr;115713 said:
Pores, meaning Stomata? Most aquatic plant stomata are non functional.

If you go from say a TDS of say 100 to say 300 rapidly, then maybe.
But dosing ferts would accomplish this same thing vs saya water change

Using the fert salts, we can change the osmotic potential outside the plant.
But plants are very good at regulating things endogenous vs exogenous conditions.
You'd have to really push things pretty high to get a significant effect I would think.

Fish will have the same issues, they do not seem to mind.
 
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Matt F.

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You're making the assumption that osmotic pressure is the cause of plant growth based off whether or not you can see so called pearling (induced by in increase or decrease in gh). This introduces a major confound in your hypothesis, which would need to be accounted for. So, "pearling" is central to your argument. It's what your basing your osmotic pressure hypothesis on. We're telling you that you'll get wacked results b/c the water you are introducing holds more O2 than the tank water; hence, the perceived bubbles.

Solcielo lawrencia;115675 said:
The change in osmotic pressure is what's causing the immediate pearling while adding fresh water. I first noticed this when I mistakenly added too much CaSO4 and MgSO4 to the tap water weeks prior and no pearling took place as it usually does. Yesterday, I did a 90% WC and added less GH and noticed it pearled a bit more. Then today, I did another 90% WC and didn't add any GH and it was pearling even more. All of these recent WC were done at night, 8pm, without any direct light source. I'm pretty certain I can induce pearling in complete darkness so that the gas escaping from the plants is not the direct result of photosynthesis.

So can the change in osmotic pressure be the cause of the increased plant growth?
Can others confirm that it's osmotic pressure by varying the amount of GH to the fresh water during a WC?
 
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Mar 20, 2013
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Matt F.;115719 said:
No, there is a difference between streaming and pearling.

Streaming occurs when you break a part of the plant or trim. The gas escapes from the open wound in a stream of bubbles. Sometimes the bubbles come out at 1 bps. Other times it's faster or slower. You see a stream of bubbles from the same origin (a damaged portion of a plant or a freshly cut stem).

Streaming is just O2 rising to the surface at metered intervals. It can also occur on non cut stems, as I have just seen from the HC. Also, since I closely matched the amount of GH added, no gas bubbles were formed at the HC, unlike the previous three days. Just some pearling/streaming.

Again, I did NOT say that pearling is an indicator of growth, even though it is as a result of photosynthesis. Please read what I wrote and not what you think I wrote. Just because the word pearling and growth are in the same paragraph does not mean I said pearling results in growth or whatever. This is the third or fourth time I said this.

Anyway, I found the answer to my previous question about tonicity. Yes, even plant cells lyse or crenate due to changes in osmotic pressure.
 

Yo-han

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Solcielo lawrencia;115724 said:
Streaming is just O2 rising to the surface at metered intervals. It can also occur on non cut stems, as I have just seen from the HC. Also, since I closely matched the amount of GH added, no gas bubbles were formed at the HC, unlike the previous three days. Just some pearling/streaming.

Yes, streaming are just bubble rising to the surface whether or not O2, but it is NOT pearling! If it happens on an uncut leave, the leave is still damaged, maybe just a very small hole made by a shrimp or whatever, but it is not what is known as pearling. Bubbles after a water change, whether or not on plant leaves, is NOT pearling. Pearling is when you see bubbles on the leaves without any changes and solely from photosynthesis. Fast growing plants are more likely to pearl, closer to the light leaves are more likely to pearl and with less flow plants are more likely to pearl. Whether or not osmotic pressure has anything to do with real pearling I don't know. Streaming is not from photosynthesis! Perhaps the change in osmotic pressure popped an air vessel -> streaming.

No offense to you, just to make clear in general.
 
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Here are pictures of the pearling over three consecutive days' water changes. Each water change was 90%. I did not take a picture of last nights water change because there was no pearling. Below each picture is how much GH added to the fresh water during the water change. Fertilizers added after the water change include NPK in roughly the same amounts.

[attachment=1555:name]
3/5 tsp of CaSO[SUB]4[/SUB] and 2/5 tsp of MgSO[SUB]4[/SUB]

[attachment=1557:name]
2/5 tsp of CaSO[SUB]4[/SUB] and 1/5 tsp of MgSO[SUB]4[/SUB].
There are even more gas bubbles on the HC.

[attachment=1556:name]
2/5 tsp of CaSO[SUB]4[/SUB] and no MgSO[SUB]4[/SUB]
This last photo shows that the gas bubbles are the largest probably because I added the least amount of GH.

Also, considering that last night's (7/1/13) WC (GH matched closely with the previous days' concentration) had no pearling like the ones seen in these pictures, that pretty much debunks the high gas concentration of tap water forming on the plants.

062813.jpg


063013.jpg


062913.jpg
 
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