View Full Version : Plants and pearling

11-17-2016, 03:34 AM
Hey guys, I have a question about a discussion I have with a friend which is so difficult to put it so both of us are satisfied that I will have to explain the whole dispute. I have googled the answer but the answer I get does not satisfy my friend due the fact that he wants to see this specific case.

I have a newly setup tank, scarcely planted (picture in the end), no fish, nitrite's spike, no water changes, homemade CO2 at 2 bubbles per second, canister filter, spray bar submerged so it makes waves but with no noise (its in my bedroom), 82 degrees temp, 16 d gH, very high nitrites and nitrates, 80 gallons per hour filter, 25g tank, ph less than 7, over 6.5, 60 watt home made fluorescent lighting consisting on 3 bulbs of 20 watts each rated 1200 lumen each of cold white light (rated 6500 K I think) immediately over the tank, separation of bulb from the water of no more than 2 inches (u will see in the picture), all nutrients SHOULD be high since I dosed before setting it up, the first plants have less than a week and 99% of the plants are leftovers from friends, mainly from pruning, plants have new shots, I observe growth but I'm not expert to say if its a lot, too less or normal. Got some diatoms spike as well in some parts of the substrate (got a microscope, corroborated those are diatoms), tank has been there for about 3 weeks, plants been there for about 1 week.

I think that's all the info you would need.

My plants do NOT pearl, I only see a bubble from time to time but not even close to what pearling is. The question or the facts debated are as follow:

My friends position: More light = more photosynthesis and so more oxygen created, my plants (very matured tanks of 10 gallons DENSELY planted) do pearl, so the conclusions are these:

1st.- My plants are each producing more oxygen than yours because I have better lightning and the demonstration is that mine pearl and urs not
2nd.- If you had a better light ur plants would be pearling
3rd.- Pearling is the measure of how much oxygen ur plants produce so if ur plants do not pearl and mine do, that means ur plants are producing less oxygen than mine or else they would pearl the same or more than mine.

4th.- after all that, its obvious that u need a better light

My position: We agree that more light = more oxygen production cuz of more photosynthesis (oc with a saturation limit) but pearling is not a measure of how much oxygen a plant is making since pearling depends on the oxygen saturation of the water tank, so my conclusions are as follow:

1.- The fact that my plants do not pearl do not necessarily mean that ur plants are producing more oxygen than mine, they could be producing the exact same amount, u just have more saturation of oxygen in ur tank given the amount of plants or the filter or whatever other reason and thats why u have pearling, not cuz ur plants are producing more oxygen.
2.- Increasing the light does not necessarily mean my plants will pearl and I actually think they wont cuz I think the problem is oxygen saturation in this case given the amount of plants I have and the cycling, also that the plants were planted a week ago from cuttings I got for free.

He denies my version since he says a single stem plant in my tank should pearl YES OR YES given good nutrition, good light, good CO2, a single stem should be enough to saturate the water so pearling is observed

I proposed a little experiment to him to corroborate which he accepted: I wont touch my aquarium for 2-3 weeks. In this period the plants should grow, have accustomed to the new environment and also the amount of bacteria will stabilize, the amount of nitrites and ammonia will drop and so the oxygen consumption will decrease thus activating pearling in my tank without changing any light nor nothing. He says it wont cuz the problem here is light. Will attach pictures of the tank in question (PS: I will upload this post to another forum as well to have as many opinions as possible in case some of u r there too)


11-17-2016, 07:30 PM
I have a 33g dirted heavily planted tank with a Beamswork 1w x 54 6500k LED, 2 years established without ever any co2 or Excel and some stem plants (not all though) will pearl in the middle of the 6hr photoperiod, so I don't think it's light. The tank just has to be doing really well, balanced. I think you'd need more fast growing plants with all that Nitrate.

Just my 2 cents

11-20-2016, 05:44 AM
could it be that, depending upon how recently your tank was set up, the plants still may be in an adjustment phase? If they are freshly planted with poor root systems and whatnot, it may take time for them to settle in and reach their "expected" photosynthesis rate.

11-20-2016, 04:03 PM
Regardless of what you decide to do with your lighting (leave it, change it, do whatever makes YOU happy with YOUR tank) you've done a fabulous scaping job in here. I like the 'rocked-in borders of the berms' look a whole lot.

Please do keep us updated and best wishes for the rest of your cycle to complete. I hope to be able to follow and watch you continue to put this tank together.

11-20-2016, 04:38 PM
I agree with RG, your tank looks great.

11-21-2016, 10:36 PM
plants havent been there more than a week or so and the tank itself has less than a month

11-22-2016, 12:52 AM
Hey there, Skirmitch!

You are correct.

A single stem plant will not pearl. Unless, of course, that single stem is in a small cup of water. You are absolutely correct in that you have to reach complete O2 saturation. As you said, we can all agree that using high light, fertilizers, and carbon supplementation will help raise the rate at which photosynthesis is occurring in a plant, but there is no way a single plant in any decent amount of water will pearl without tricks. The O2 produced by that plant simply cannot produce enough oxygen on its own to saturate the water and keep it saturated.

If your friend needs validation, ask him to watch his tank(s) as soon as the lights come on. By his reasoning that light, alone, is responsible for pearling, then his plants will magically start pearling within moments of the lights coming on. In reality, that is not the case. The lights will come on and he will have to wait some length of time before the plants saturate the water with enough O2 before he sees pearling.

If your friend needs a visualization to help him understand, use a pot of water, two measuring spoons (1 tablespoon, one 1/16 teaspoon), and salt. The pot of water represents the aquarium, the spoons are the plant(s), and the salt is the oxygen. Salt will dissolve into water, just like oxygen does. Fill your pot up with a quart of water and imagine the pot is your friend's aquarium. Start adding salt, a tablespoon at a time, and stir until it is dissolved completely before adding each new tablespoon. The large tablespoon represents the large amount of plants he has in his small tank. Be sure to keep count of each tablespoon added. At some point, fairly quickly, you will no longer be able to get the salt to dissolve in the pot of water. As you guessed it, it is because the water has become so saturated with salt that it simply cannot absorb any more. The excess salt will simply sit in the bottom of the pot until more water is added. This will happen fairly quickly as his small volume of water (10g tank) simply cannot handle so much salt (oxygen) being added so quickly by the large spoon (plants).

Now have your friend repeat the experiment, except this time have him fill the pot up with double the amount of water, and use the 1/16 teaspoon. This now represents your larger tank that is populated with just a couple of plants. Tell him to start adding the salt by 1/16 teaspoon at a time, stirring until each one is dissolved, and that he needs to keep track of how many of those little doses of salt that it takes before the pot becomes so saturated that he can no longer dissolve any more salt. Once he understands the directions, you can go take a walk around the block or read a book, because he's going to be busy for a while. :hmm3grin2orange:

Hopefully he "gets" it without having to do the whole experiment. When he does, also point out that there are other processes going on with the fish tanks. Not only does surface agitation cause CO2 to vent out of the water, but when the water is super saturated you will also have the oxygen off gas until an equilibrium is reached. So even if your single plant could somehow saturate the water with oxygen during a single photoperiod, the gas exchange at the surface will happen quicker than that single plant can generate more oxygen.

I hope you can help your friend see the light on the issue haha

I love that tank. Such a great scape!