Pearling in the morning but not in the evening?

[JoeBanks]

My tank has the odd pattern of strong pearling within minutes of the lights coming on in the morning, but the pearling slows down to almost nothing by evening. What could be causing this?

Tank stats:

180 gallon
495w pc lighting
EI Dosing
CO2 injection during the day (PH 7.8 drop to 6.2), air injection at night
gravel thorughly cleaned one month ago
medium fish load

 

[VaughnH]

Re: Pearling in the morning but not in the evening?

Have you checked carefully to be sure you really are turning the CO2 on in the morning and not off? This sounds like you run the CO2 at night with air stone going, then turn it off with the lights in the morning.

 

[JoeBanks]

Re: Pearling in the morning but not in the evening?

I'm sure about the CO2. I have a PH controller bringing the PH down to 6.2 during the day. The CO2 turns off when the lights turn off at night. The PH is around 6.6 in the morning before the CO2 turns back on.

The one thing I've noticed is that if I leave the air pump on during the day together with the CO2, I get better pearling in the evening. I know that pearling increases oxygen saturation, but can oxygen saturation have an affect on pearling?

 

[Wet]

Re: Pearling in the morning but not in the evening?

Do you dose nutrients lean? Do you dose after lights out?

We see pearling because of O2 saturation. Otherwise O2 from the plants just disolves into the water column.

 

[VaughnH]

Re: Pearling in the morning but not in the evening?

I'm sure about the CO2. I have a PH controller bringing the PH down to 6.2 during the day. The CO2 turns off when the lights turn off at night. The PH is around 6.6 in the morning before the CO2 turns back on.

The one thing I've noticed is that if I leave the air pump on during the day together with the CO2, I get better pearling in the evening. I know that pearling increases oxygen saturation, but can oxygen saturation have an affect on pearling?

Pearling is a result of oxygen saturation. Once the plants respire enough oxygen to saturate the water, the oxygen collects on the leaves to form bubbles.

Just brainstorming here: what if the solenoid is stuck open? And, the bubble rate is a bit too low. You have some CO2 going into the water at night, but the air bubbles drive off a lot of it. In the morning, the air pump goes off, allowing a rapid rise in CO2 in the water - thus pearling starts. My solenoid failed in the open position some weeks ago, and it took quite awhile for me to notice it, because the CO2 flow was not readily visible. This doesn't seem to explain the drop in pearling as the day goes on, though.

 

[JoeBanks]

Re: Pearling in the morning but not in the evening?

I dose standard amounts each morning. I do two 30% water changes per week.

My solenoid is working properly. The CO2 is off at night, but the PH only rises from 6.2 to 6.6 (degassed water is PH 7.8)

The idea of O2 dissolving into the water before we can see it is a concept I never understood. During strong pearling, there are steady streams of bubbles coming from the plants. I can't imagine that in low O2 situations, these streams of O2 are dissolving so quickly that we just can't see them.

Or do plants also produce O2 that is not visible and pearling is just the excess? Can anyone clarify this?

 

[JoeBanks]

Re: Pearling in the morning but not in the evening?

In response to my own post:

If I assume that visible pearling only occurs when the water is saturated with O2 (which I still don't understand the reason for), then the most likely explanation for this "reverse pearling" pattern is that there is something decomposing in my tank that is absorbing all the oxygen.

I thoroughly vacuumed my gravel last month, so it can't be that.

I clean my filter once a week so it can't be that.

My only guess would be a large piece of driftwood that I added to the tank 3 months ago. The base of the wood has white fungus growing on it which I'm assuming means that the wood is decomposing in those areas. Could this be causing it?

 

[Wet]

Re: Pearling in the morning but not in the evening?

What are your nutrient levels? You may find it interesting that I see pearling whenever I add KH2PO4, even with moderate-high PO4 available, no matter the time in the photoperiod (save for the first and last 15 minutes or so). Try dosing a few hours before lights out: if you see pearling, then it is probably nutrient related, and you can narrow down whatever runs low at the end of the photoperiod. Just a thought.

An attempt at explanation until our guru shows up: It is common to see bubbles streaming from damaged plants, be it from trimming or pinholes from deficiency or whatever. But pearling is a little different, where oxygen seeps from and clings to the leaf as long as possible before floating away. This oxygen cannot dissolve in the water column and so just clings to the leaf until physics takes over and it floats to the surface. If the enviornment is not saturated with O2, we never see these bubbles.

For example, there are many tanks with healthy plants and no visible pearling. This does not mean the plants aren't in photosynthesis.

If your tanks are streaming in the morning and not streaming at night, it is *possible* that they may be suffering minor damag by animals at night, and by the end of the photoperiod they have repaired themselves. Something similar has happened to me with clumsy loaches.

Hope this helps some.

 

[Tom Barr]

Re: Pearling in the morning but not in the evening?

If you see good growth/pearling eariler..... and then it slows down or stops later in the day, try lowering the light for a couple of days and see if the pearling presist longer..........but lower.

Sounds like you are limiting on CO2 to me.
Pearling declines virtually always are if it is a daily thing.

Your plants have enough to get going initially, then they remove it all from the water, by the time the CO2 system catches back up, the lights are going out.

Try this: increase the flow to the CO2 system, add at least 2 reactors/outputs at opoosite ends of the tank.

You need to increase mixing and flow of the CO2,.

Regards,
Tom Barr

 

[JoeBanks]

Re: Pearling in the morning but not in the evening?

Wouldn't my PH go up as the CO2 is used up? My controller keeps the PH steady at around 6.2.

I'm injecting CO2 into the system just before my pump, then back into the tank on 2 opposite sides through the pump outputs.The PH drops very quickly when the CO2 comes on in the morning and stays low all day. I recently tried to lower the PH to 6.0 but some of the fish were showing signs of distress so I raised it back up.

I'm also dosing excel every morning to supplement the CO2 in case that was the problem, but it doesn't seem to have an effect.

Overall, since I started EI dosing 3 weeks ago, there is a dramatic improvement in the health of my plants, but coming home to a tank with no air bubbles in it at the end of the day keeps giving me the feeling that something just isn't right.

 

[Bill]

Re: Pearling in the morning but not in the evening?

I have a sump on my tank and if I let it get to low where air is being sucked in at the pump and mixed in my CO2 reactor before returning to the tank I get a lot of pearling.

I would guess that since you are injecting air at night that you may be close to saturating your tank with the oxygen. Then in the morning when your CO2 comes on the pearling starts because the tank is close to saturation from your nighttime oxygen injection but as the day goes on you lose the saturation from the nighttime oxygen injection and your pearling stops.

Maybe you could turn off the oxygen injection for a night and see if the tank starts pearling first thing in the morning.

So I would try raising the CO2 some as Tom suggested.

Bill

 

[JoeBanks]

Re: Pearling in the morning but not in the evening?

I'm maxed out on CO2. I would add more, but the last time I checked, having dozens of dead fish floating around the tank may lead to an algae outbreak.

Seriously though, if my tank stays exactly as is, I am very happy with it. With EI dosing, I can finally grow any plant I want. Even my HC is thriving - I was never able to grow it at all before. I just wonder if the lack of pearling is a sign of bad things to come.