Plants release lot so of Oxygen when . . .

[AngelPeace]

Dear friends,

I am cycling my tank and getting all my water parameters right for the plants, then I will add stock. So currently no stock allowing me to mess around a bit and get things right. So I added way too much NH4 (ammonia and then NO2 and NO3 went through the roof, opps!! Its why I spend ages getting things right without stock).

I should add, I have a 100L tank and 120L RO storage tank. I dose the storage tank with GH and KH only before doing a water change.

Noticed a weird thing, when I do a 100% water change, suddenly my plants start to pearl, ie lots of oxygen gets released (see pic below). Not sure why. The water the change I did has increased levels of KH and GH, and reduction of NO3 but that's about it. Once I do my water change I add micro nutrients as seen in the table below. But the plants produce loads of oxygen BEFORE I add micro nutrients so cant be that. The tank had a very high concentration of nitrate (I am adding NH4 manually as I cycle the tank and I added too much as mentioned above). See all my values below.

So wondered if it was related to either KH/GH change, NO3 reduction or something else. Below are all my values and also shows when the water was changed. I read that in general very high NO3 levels is okay for plants (of course lethal for fish and best to keep below 20mg/L). The first time it was over 200mg/L , when I did a water change the plants went mad, was lovely to watch. Then this morning I checked, and NO3 was still at 60mg/L so I did another 100% water change and once again the plants went mad!!

(water parameters of aquarium)


(water parameters of RO storage tank)


When I complete a 100% water change, the PH goes from 7.5 to 6.5 over time but I think that is the Co2 injection and the ADA v2 soil which buffers the water and lowers PH.

Thought maybe the plants wanted a higher PH, so when I added the new water (was 100% water change) they temporarily thrived in the more alkaline PH, then the CO2 and soil lowers it and once again the PH is 6.5 (ish) which could be too low and they stop pearling. The plants I am mainly referring to is Monte Carlo. Seems to go wild after water change!!

(Monte Carlo after water change)


I should also note I am using a drop checker to ensure I am injecting the correct amount of CO2.

Any help appreciated!

[fr499y]

Plants will pearl after a water change which iirc is to do with the saturation of oxygen @black ghost is that correct?

[AngelPeace]

Plants will pearl after a water change which iirc is to do with the saturation of oxygen @black ghost is that correct?

Hmm, they produce Oxygen, not consume it while the lights are no, so not sure I follow. The water added from RO storage tank will have a different level of Oxygen in it, likely much less. Does that mean its then easy for plants to expel more O2 than before perhaps?

I was hoping it was due to reduction of NO3, increase of KH (which allows the plants to use up the Co2 apparently). Wish I had taken up science instead of IT haha

[AngelPeace]

my KH dosing is potassium carbonate btw

[Gingerlove05]

Plants will pearl after a water change which iirc is to do with the saturation of oxygen @black ghost is that correct?

I remember something about that can’t remember off-hand exactly what it was.
But when you add water to the tank the movement of the water will trap oxygen and co2within the water, the leaves will also still produce oxygen, so as the water flows around all the oxygen will accumulate causing pearling. The extra co2/co2 injection will also help as this aids the photosynthesis process

[AngelPeace]

hmm but additional Oxygen circulated wont cause pearling surely. I mean, plants dont need Oxygen during the day, they produce it! So surely the theory here would be related to gaseous exchange (ie Co2 in the air mixing with the water and being consumed by plants). But that still doesnt make so much sense as the water before the water change was already saturated with Co2, and no pearling was happening.

[AngelPeace]

I know there is a lot more Co2 in the air than there is in an aquarium even if its saturated to the recommended levels (based on a drop checker). If that theory that you cite was true, then if I increase Co2 levels even more (so the drop checker goes yellow (ie overdosed) then the plants should start to pearl. But not sure they would.

Thank for your replies so far guys its really appreciated.

[black ghost]

Plants will pearl after a water change which iirc is to do with the saturation of oxygen @black ghost is that correct?

Erm… yes. Pearling occurs when the plants are producing oxygen faster than it can dissolve. Water change water tends to be well oxygenated, presumably more so than the tank, so less oxygen from the plants can dissolve for a while after the water change.

[AngelPeace]

Oh I see, all the parameters I spoke of above have nothing to do with it lol.

It’s just there is so much oxygen in the water (tons of agitation as it goes in that no more oxygen can dissolve so it appears as pearls.

Gosh, that’s interesting, but how do I get them to pear all the time. Need to be a scientist to work that out.

[black ghost]

Gosh, that’s interesting, but how do I get them to pear all the time. Need to be a scientist to work that out.

Just give them too much oxygen in the water. But why would you want to..,?