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BarrReport post i wanted to share

6K views 35 replies 12 participants last post by  HD Blazingwolf 
#1 ·
Qoute : Tom Barr aka PlantBrain
""Why water change day seems to grow aquatic plants better
Basic simple question: why do my plants seem to grow better/best the day of the water change?

I do a large water change in the morning right after the lights come on, then late in the day, there is mad pearling and obviously better growth than any other day of the week.
I've measured plant growth to confirm this also. (stem length and biomass).
I've also done back to back water changes over the entire week, once a day, same time.

I've suggest a few hypothesis:

1. CO2 rich tap water. This is supported and suggested in the Optimum Aquarium(1986) from Dupla's Horst and Kipper, often around 20-30ppm ranges.
One can/could test this by allowing the water to sit for a 1-2 days to degas, then change the water.

Results, we still see an increase in growth.......but this is inconclusive.
I agree there is some strong effect here.

2. Temp differences within a sealed hot water heater and cooler tap water degas once released into the aquarium= cool water holds more gas, O2 and CO2 etc. Same issue as above, plenty of gases available to help growth. Test similar and similar results to above #1 as well.

3. Exposure to air. Plant aerenchyma (think a sponge in water and squeezed, and then out of water and squeezed) acts like a sponge and takes up lots of gas/air and then uses that while exposured during the water change. Larger water changes seem to produce this effect.
Test: large water changes by continuous drain and fill methods vs big drain and then refill after exposure. Seems to be plausible. Results suggest the same. You still need to allow and account for the degassing of the tap water also.

4. Indirect O2 addition= > drives bacterial cycling much faster= . indirect impact on plant growth.

5. Gas films. This was discussed by Ole in TAG, vol 23, No#1, pgs 32-39
A physical gill that improves submersed O2/CO2 exchange in some wetland species. If you add enough CO2, then the gas films do not have any difference in growth rates with/without the gas films(see Fig 7). This is similar to exposing the plants to air during the water change.
www.BarrReport.com

End Qoute!!!



i thought i'd add to this and share here, that my water degasses for a whole day now in a big garbage can. water is brought to close to room temperature and i replace 80% of the water in my sump and in my tank.
water is 76 degrees going in, tank is kept at 78/79

there is no extra oxygen as i jsut have a small pump in the garbage can.
water change is done without lights or co2 on but after the water change is done, plants look "better" i think we can all agree to this, no nutrients added, no co2, no lights, but my plants look awesome.

everything is turned on, lights hit and boom bubbles bubbles everywhere.
there is no saturated water for this to be fake pearling. and don't get me wrong my tank is a sodapop tank every day, but this is just madness



its a stupid hypothesis, but i think plants just like clean water too :)
 
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#4 ·
There was ample post discussion beyond the quote.

As mistergreen suggest....some tap will have more, and some will have less CO2........surface waters will almost all have lower CO2, well waters will generally all have higher CO2 content.

Some might provide a limiting nutrients, other tanks might not have any limitations..........

etc..........

In each case, there is a good chance that the aquarium looks better after wards.

O2 is almost always higher with tap and vat/reservoir water vs tank water unless it's done the latter 1/2 of the light cycle.

The other hypothesis is perhaps O2 demand by the tank water and consistent export of that, leaving more O2 available that would otherwise be used by micro inverts and bacteria to break down organic matter/waste.

Which could explain a lot regarding daily automated water change systems.
I've installed a few and they seem to be without any issues over long long time frames.

The gas film issue could also provide some insight/support into CO2 mist hypothesis.
 
#5 ·
yes there was PLENTY of discussion but as im not a member i couldn't addon.. so i wanted to start the discussion here

and just to add my two cents. i completely agree plants look better.. oxygen? sure believeable
plants exposed to rfesh air also possible!
and maybe they like clean water too free of other stuff plausible as well

maybe its more a combination

but it is pretty apparent like you said tom, plants do like water changes
 
#10 ·
You know what else "pearls" after a water change? My glass, my heater, even my hands if I was rescaping.

And what do you mean by "Looks better"? It might just be that crystal clean water you just added.

I always thought that aquatic plants needed some time before showing an improvement on their health.
 
#11 ·
You know what else "pearls" after a water change? My glass, my heater, even my hands if I was rescaping.

And what do you mean by "Looks better"? It might just be that crystal clean water you just added.

I always thought that aquatic plants needed some time before showing an improvement on their health.
my water is crystal before and after the water change.. i change 80% weekly. my filter pads bi weekly, and i fluff all my plants bi weekly to keep debris off them and into the filter pad
my water comes out almost as clear as when i put it in
 
#18 ·
my tap water isnt special.. i dose fertilizers directly after my water change... but plants definitely grow better that day, and they do pearl significantly more that day vs other days


similarly i also have a wet/dry. so oxygen levels and co2 are kept pretty stable day after day.

i wonder if we drain tank water in a bucket every day, and then fill it back up with the same water if it would have the same effect????
 
#21 ·
Probably.

But you expose the plants to air, and like sponges.....they will take up a lot more air and CO2 than we think, many tidal places have excellent plant growth both marine and freshwater tidal locations.

Those places get 2x a day water changes and exposures.

And we have excellent plant growth in those same places.
 
#19 ·
If I may add this : Takashi Amano does a lot of water changes. I have 2 of his books, he does 50%, sometimes 33% water changes in all of his aquariums, but mostly 50% wc each week.

As for myself, I do not do a lot of water changes, I am too lazy. I have a planted 7 gallons, with one 33% wc each 2 months, I do not have algae issues with it.
 
#20 ·
Whether it's EI or ADA (Amano) the water change is part of the overall system. Anyone can have a tank free of algae without a water change the point is it's usually a limited system. Regular water changes increase the range of light, plants, scape, etc. It allows more 'mistakes' we all do them. It becomes a more forgiving system.
 
#23 ·
This is a good experiment then!!!!
FOR SCIENCE!!!

ur probably right, its due to being exposed to air.
i so badly wanna think that they just like clean water though... maybe just cause i like water change day so much
Lots of magic in fresh water isn't there. Plants pearl, fish spawn, life is sustained. You don't have to hit me in the head with a brick that says "Do a water change"
 
#26 ·
Unfortunately I don't have much to add to this, but I do think it is an interesting discussion. I too have noticed that plants seem to have their leaves out a bit more later in the day after water changes. When I switched to mainly RO water (~15% tap, sitting out for several days) I expected it to go away, but it didn't. There isn't much in my water, but the plants are exposed to air for a while and there is a ton of splashing when I put the new water in. Perhaps several of these conclusions are valid which is why removing just one doesn't stop the phenomenon?
 
#29 · (Edited)
Hello, there is also this article from PPS-Pro, which seems to contradict the frequent water changes thinking :

https://sites.google.com/site/aquaticplantfertilizer/home/water-changes

I must say as for myself, I am not quite convinced one way or the other. Are frequent water changes really better?

This summer in my ancient apartment, i had cyanobacteria booms after water changes, maybe it was the tap water there or the fact that water was hot in the summer?

Anyway thank you for sharing this article from Barr's Report. It is very interesting.

Michel.
 
#30 ·
Hello, there is also this article from PPS-Pro, which seems to contradict the frequent water changes thinking :

https://sites.google.com/site/aquaticplantfertilizer/home/water-changes

I must say as for myself, I am not quite convinced one way or the other. Are frequent water changes really better?

This summer in my ancient apartment, i had cyanobacteria booms after water changes, maybe it was the tap water there or the fact that water was hot in the summer?

Anyway thank you for sharing this article from Barr's Report. It is very interesting.

Michel.

big water changes are beneficial whether its a fast growing tank with lots of fishies or a tank that is slower going. the slower growth tank however will be more forgiving in the long run
on tanks that recieve less fertilizing, feeding, have lower stocking levels and slower growth, frequent water chagnes aren't as necessary as the system is slow enough to respond to everything happening. plus not much is being added to the tank that needs to be later removed
 
#31 ·
Here's another piece of evidence for our puzzle. Today I did a large water change (~80%) in my 75 (which has a 29 gallon sump). I did the water change a couple hours before the lights came on, used pure RO water, and forgot to add the ferts. I came back a couple hours later (just after the lights came on) and noticed all of the plants covered in bubbles, leaves open, etc. One error I made is that since the RO water is stored in a large vat in my basement it was ~67*F rather than the ~75 my tank stays at.
 
#32 ·
Another idea might have to do with the water level change makes a pressure differential in the cells. When you lower the water level, the pressure on the cells goes down and "stuff" from inside the cell is expelled (unless it is perfectly elastic). When the water level goes back up, the pressure differential forces "stuff" from the water column into the cells.

The cells do that on their own anyway don't they? Maybe the water change just supercharges it.
 
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