Now when you mention this there was a time when I always changed my water with one hose (siphon) coming out of the tank and one with fresh water into the tank - without altering the water level.

No pearling. We have < 0 ppm CO2 in our tap due to hydroxide treatment, and very low nutrientlevels.

Since I started to do ordinaray wc:s where I lower the surface to just a couple of cm from the substrate the "after wc champange" have started again... Hmm...

Yes, lime softening removes the CO2. So that make's sense. Some water companies recarbonate the water and lower the pH, essentially adding CO2 to the tap.

If not, there's not going to be hardly any CO2, a high pH and very soft.
Most blend the softened water with the un softened water in partial lime softening methods. This way they can avoid recarbonation.
But the tap still has very low CO2 though but decent pH and they can produce more soft water, btu not super soft.

The hydroxide also will mess with the pH/KH as it adds some OH alkaninity, which will make it seem like you have 200ppm and fish are fine and plants grow well.
Limestone regions will often do this and have CO2 tap water issues with aquarist.

Try this, time the exposure to air, and use a spray misting bottle to keep the plants moist/splash water on them every 10 minutes etc.

Try for 5 min, then for 30min.

You can clean the tank really good while the tank's low(not a bad idea anyway!).
If you watch, and add black cloth blocking the lights on one side of the tank, then refill, you should see dramatic pearling only on the side with the light.

That will essentially prove it's the exposure to the air.
You will need to replace the tank water without the exposure to air also as a control and see how the black cloth effects the plant's pearling.

So this may be a good reason to do large water changes
Even if the CO2 is low in the tap.

It'll also give a standard of what optimal growth and pearlign is, so folks can try and get that same effect all week long rather than for a day or two.

And one thing that it will show more support for is that the idea behind the gas phase in CO2 mist, is well supported here. => 30-40ppm of Dissolved CO2 in water is not the maximum growth attainable. We can grow things even better with CO2 mist.

My personal goal is not max growth rates, it's max growth for lower light. I prefer to use less light to throttle growth rates as well as judicious plant choice. This provides the best mangement and the most stable method for a tank.

But knowing all this helps to focus the needs of other folk's goals, who may not want this.

Regards,
Tom Barr

I don't use a misting method, I use an in line reactor with a dedicated pump. I do get pearling later in the day, similar to water changes but it seems to take a while to develope that pearling. With large water changes I get a lot of pearling and it takes about 20-30 minutes. I called in a couple of favors to borrow a DO sensor, but, Tom how did you use the O2 levels to calculate CO2, won't that depend on plant concentrations and types of plants? I am curious to see where the CO2 concentrations settle out. And in the end if I should need to make a change with the method of delivery. I don't have any problems(major) with algae. There's a certain level of algae, that I don't care much about.

Sorry, this is an aside...
I tried to post a picture to show it but, couldn't, I guess the format is wrong. Which format do i need?

You do not use DO to measure CO2.

O2 levels are correlated with plant growth.

So say a tank with one CO2 method produces say 110% saturation of O2 at a given temp at 8 hours after lights are "on".

The same tank with CO2 mist produces this same level after 3 hours of lights on and then rises to 140% at 8 hours after the lights are on.

Note, this is the same tank, flow characteristics, just one day you do the normal CO2 method, then the following day the CO2 mist method.

That difference in the O2 levels and the timing is due to the CO2 mist effect.
As long as the nutrients levels are non limiting(eg: EI dosing) and light are the same in both cases, then the rather large change in O2 production by the plants is due to CO2.

Plants grow based on light, CO2 and nutrients.
There's plenty of water obviously so that's not considered.

Tank changes between the light/nutrients/plant biomass/current/temp are minimal in the same tank between one day vs the next day.

You can run a control to a see if you wish there as well.
I know what the control does and it tends to stay pretty stable in terms of O2 production difference in 1 single day, they do not change much.

so if you change the CO2 method between one day and the next day and see a huge jump in the pearling and O2 levels, then that is telling you that's very likely the CO2.

O2 meters measure just that, not other gases.
O2 is the best measure aquarist have of actual plant growth althougnh dry weight and a very accurate scale would be nice and correlation of wet/dry weight sand plant parts etc would be nice and nutrient extractions etc.

See the "Phytometer" MS word doc here for more info.

===============
So using this same method with the O2 meter: remove say 70% of the tank water and not expose the plants to air. Save this same water. Add back to the tank. Measure O2 levels.

Next day do the same thing except remove 90% of the tank water and expose the to the air. Wait 5-15" min mist with some water to prevent dessication. Refill with tank water. Measure O2 levels afterwards over the same time frames(not one discrete point, rather, several for both treatments).

I had 28-52% increase for O2 for the CO2 mist method and about 40-60% for the air exposure treatment. That's a lot more growth increase than folks normally ever see.

That's why mist causes too much growth and too much pearling for many folks.

Formation of O2 bubbles also forms on the top portion next to light where photosynthesis occurs 1st in larger tanks . If it was mere degassing, we'd see bubbles everywhere, but I do not only on the plants closest to the lights and then with time, the plants progeressively farther and farther from the light source.

The plants are exposured for 1 hour and are misted till the refilling neat the top and less so near the bottom.

So is it due to the light distance or the air exposure?
I'm not sure but it seems reasonable to suggest that some of both. How much pearling growth will we get out of a ceertain time of air exposure?

Seems like a little for little exposure.
Or a lot for a longer peroid.

That sounds reasonable.
Without doing a lot of measurements, it'll be hard to say.
Even then generalizing would be tough.

Still, try this exposure to air for say 15" minutes and watch the tank.
Try it 2x a week for 2-3 weeks and see what happens to the tank's health.

It'll shoot through the roof.

My goal here is two fold:
Look at CO2/how the gas phases might be of use to us and to help folks with potential CO2 and algae issues get rid of it.

I noted that Cladophora and other species fo algae took a beating and stopped growing etc and some died off as a result of this treatment in a friend's tank.

It'll not help the algae, so it's worth a try and see the effects.

I trust most folks here can tell the difference between pearlign and degassed bubbles.

I'm not going to bother explaining this to other folks out side the BR. I just do not have the time.

Regards,
Tom Barr

Sunday is a day for water change, so I changed water (tap water) in my tank without my lighting hood, because i had to repair my light (bad contacts). My lights were off, and after water change I saw outgassing bubbles in my aquarium without the lights over it, it look like real pearling from the plants. This was not real pearling, but this may be the reason for better and much more intense pearling after water change, outgassing bubbles in combination with real pearling ?

Turn off your lights, after water change to check your bubbles...

Try this, turn the lights off a day first.
Then do it.

You have a fair amount of O2 still being given off if you turn the lights out before doing the water change. Look at where the pearling is occurring.
Then place the light back on and note where pearling occurs.

Regards,

Tom Barr

I`ve changed water in my tank in the morning without my lights, then I started with one neon light 18w (only to be able to see what is going on)... I saw, that lot of tiny bubbles were created under all leafs, after water change. "Pearling" started from all my plants including glossostigma...Plants with wide leafs, released much bigger bubbles. Ludwigia repens released bubbles that look the same like pearling. After 2 hours "pearling" was almost over. Then I put back on standard 300w and I had to wait about 3 hours to see real pearling.

I think that water temperature is having great deal in pearling after water change.

Next sunday I will chage with cold(er) wather to see what is going to happen...

Misa

I just did a new round of water changes and noted some bubbles of the glass in some of the tanks.

The issue is best resolved with a DO meter.
I did note that the time it took to form new bubbles was about 15-30 minutes after the lights where on. The water change really sent the pearling into overdrive vs any night time water changes I've done.

I think many have noted this, even Amano has said things suggestive of this.
He likes to dose and do water changes in the morning, when the plants are able to use the nutrients the most and are actively growing.

Regards,
Tom Barr

I think a few things here might prevent some misunderstanding and doubt.

1. Make sure you can tell the difference between good vigorous plant growth vs mere bubbles on the plants. You should see better growth, less algae and importantly, longer persistent growth.

2. The other thing I've done and I know some of you have as well: knock the bubbles off after a water change. Wait 15-30 minutes, then look for bubbles.

3. I did 2# with the test hair grass tank. hat's the only plant in there, it does very Tell, no algae issues etc. You see a little pearling, not much, the plant really does not express a great deal and biomass in the tank is just the mat surface layer only.

I've been doing #2 for clients for many years, I do not like the look of bubbles on the glass, I like a nice clean look when I leave and have the plants growing like weeds. I always wipe the glass/acrylic down right away when I begin to drain the tank, before the water is all drained out, so that surface is clean when the water is filling later on.

I also fluff the tank good after and during a water change, Real good initially, get any detritus out of the corners, any muck, organic matter that should not be there out of the tank and netted up etc.

After refilling, I tend you swish a net around to get any leaves that might be loose, caught in the healthy plant beds/groups, any algae or muck of any sort.

Then I clean any bubbles that form and wipe the front of the glass and off to the next client I go.

I've stayed around and watched the bubbles form after this.
No bubbles reformed on the glass. Bubbles reform on the plants closest to the light first(10-20 minutes). Then progressed down into the tank.

Typically after removing/pulling up the organic matter, disturbing the substrate, O2 levels can plummet. Removal of the muck is good, after there's very low drain on the O2 due to bacteria trying to decompose all this excess muck.

This might play some role in tank's pearling better as well. Organic dissolved matter also plays a large role. I'm one of the few that discusses it.

Amano gives COD levels, which is a nicer, easier to measure parameter than BOD.
I have not done any, but I can predict they'd be much lower after a large water change and I'd be right 99/100 times.

A weekly sum total graph versus a single parameter(who knows when that measure was taken?) can tell you a lot more so please be critical on such data.

The other plausible argument for the bubbles afterwards if you do not have a DO meter/O2 test kit: The plants leaves act like a sponge with the gases, taking them all in and then releasing then slowly after wards.

Well, think about this...........
Now if it takes say 5 minutes to soak in the gas, how long does this plant keep bubbling off the gas?

1 hour? 4 hours? 8 hours of light?

Plants can take in a fair amount of gas and they store O2 in their aerenchyma for their roots, then any excess is piped out.

Algae reduction also suggest something else besides air alone is going on here also.

Many folks notice their tanks pearling like mad after a water change.
Now try this: see if you can stop or stunt this pearling via nutrients or CO2.

**Now you need not harm the plants over the long term either here**.
Just a day or two of no CO2 ought to do it.
PO4 deficiency will greatly reduce pearling also after about 1-2 weeks without much stress to the plants, some GSA and other issues might occur but not that much. Do the water change and note the difference. Give it about 4 hours, see anything happening?
You might aseea little pearling, but likely not that much.

Now, after the 4 hours, add some KH2PO4 after starving the plants a bit for PO4.
Wait 1 hour, now look?
What a difference.............

You may also use one single group of plants that normally never pearls etc, that you have troubles with etc to explore this rather than the entire tank.

I think the notion I am trying to show folks: we can amplify growth better/further/get more pearling/more O2 levels.

Is this a must for the hobby?
No!

Can it help folks and help the basic understanding of algae and plant growth?
Yes!

Is it a good clue that you might not have enough CO2 when the dramatic difference in pearling from the water change day vs the rest of the 5-6 days of the week you do not do a water change?
I think it does and can be generalized as such.

Regards,
Tom Barr