Reduced Crown width/size

[samh]

Hey guys,

Just wanting to know what would be causing reduced crown width in most plants.

I recently trimmed my ludwigia inclinata and the new growth in the crown was about half the size as it was?
It happens on a few stems and once it gets to a certain height the crowns get larger again.
I've noticed this with Pogostemon stellata, lud. cuba, lud. inclinata, nesaea pedicellata?

Is this a light issue? I'm thinking that my current lighting is low because most plants are bright green that shouldn't be green that are far from the light.

Limnophila aromatica was losing it's lower leaves. Plants like ludwigia cuba and ludwigia senegalensis are growing very nicely and fast so i'm guessing co2 is ok, drop checker is just yellow and plants pearl in an hour?

Thanks
Sam

 

[dutchy]

Light is very stable and won't be the cause of great variance. CO2 however, can vary from hour to hour. Seems to me like you have some local or temporarily CO2 issues. This might also happen just after ligjts on when the capacity of the system is kind of low.

A drop checker is a very crude device witha lot of delay. Short periods of deficiency don't show up. Pearling has more to do with light than CO2.

 

[Tom Barr]

Loss of lower leaves, small tip growth=> CO2 red flag.

 

[samh]

I thought co2 but my Cuba all range but the largest is about4-5" in diameter with good colour and leaves the whole way down. It's about 30cm long. some of the others I was trimming would have smaller crowns when say 50cm from the light but at 20cm from the light they would be much larger. Which is why I thought light. Ludwigia glandulosa is about 10cm high 4" and is about 70cm from the light and is bright green and growing very slowly. Which I was also thinking light.

I'll keep lOoking at co2 I might be able to squeeze a few more ppm by dropping the ph controller down .05

I'll see how that goes. Does water depth affect par range more so than air?

 

[Tom Barr]

If the Cuba is higher/closer to the light, getting more light and the other plants are farther away etc.........then you might have something where the one plant is beating up on the others for a limited supply of CO2.
This is CO2 competition, enough for some species, but not enough for all of them.

 

[samh]

Oh ok i never thought about that. I might trim it down lower further away from the light and give everything else more of a chance. I've noticed some species will bounce back and are more forgiving.

I've also noticed that the ph that my co2 was set at is too high.
Something i've added wood,soil etc must have changed something because i've now dropped it from 6.05 to 5.90 roughly how much ppm is .15 difference?

That previous level used to be the point where the fish would stress.

 

[Tom Barr]

No, the CO2 is LESS than you think because of those additions, not higher.

If the pH drops after you add them, it's still the same CO2.

Just the pH moved, not the addition of more CO2 by "magic" wood or soil.
A tiny amount from decomposition perhaps, but not enough to cause any significant change in a CO2 enriched planted tank.

 

[samh]

Sorry bad english I should have phrased that better. Yeah the ph changed not the co2. I've just increased the co2 myself by noticing that the ph had changed after adding wood and soil.

I've dropped the ph level set on the controller down to accommodate the change caused by the wood or soil. To increase co2.

I underestimated how much affect that putting some wood and 3l of aqua soil would have on the chemistry.

I've dropped the ph set on the controller 0.25 after the change. How much ppm of co2 is that roughly? Could that have been enough to throw the co2 level out?

 

[Tom Barr]

Folks think they have 30-40ppm without adding any CO2 all the time when using things that depress pH, but are not CO2.
False KH is another issue.

So pH is a relative measure, not absolute for our aquariums to measure CO2.

Be careful when using that metric.

 

[samh]

Yeah i understand. I don't set the ph on the controller by the ph/kh table mainly by fish and inverts.

I'm guessing the wood and aqua-soil has lowered the kh or something...? and i haven't been switched on quick enough to adjust.

I'm interested in your flow into your 120g, is it delivered by that single 1' outlet?

 

[scottward]

Good flow is so,so,so important to success!

Perhaps try a simple experiment, move a plant to a different location and see how it does?

 

[samh]

Thanks yeah I have the plants all over the Place in there.

I should clarify that plant growth and structure are great. It's only when I shorten the stems by topping that the crowns reduce.

Plant growth has been the best it's ever been. With plants like ammania gracilis and nesaea pedicellata growing well and multiplying.

I have another theory. I reduced my flow when the plants got big to stop them being blown all over the place and the plants seemed fine with it. But maybe when I shorten the plants theres room for more flowAgain?

 

[Tom Barr]

Flow certainly plays a role, I have tanks that dramatically change in flow during the weeks and between trims.

If you top a plant, then wait for the new regrowth out from the old stumps, this will be smaller. After a couple or 3 weeks later, they should fatten up some.
If you reduced your flow, then that's a big issue, the CO2 is not well mixed any longer.

You might try altering your flow so the current does NOT blown them around, but travels in a more even distribution, say under the plants, or over the tops.
I do this with my 120 Gal. The lower parts of the plants are not actively growing really, so only the top is really gobbling up the CO2.

If you used a spray bar deep in the rear behind the plants, this will send the CO2 rich water under and up and the leaves will catch the CO2 pretty effectively this way.
This works well if you can hide the spray bar and if you have surface skimming and or surface flow also.

 

[samh]

Thanks Tom, that's really helpful, I'll do that. I have a lot of flow over the top with 2 eheim 2217 flowing into each other in the middle. The the mist is going across the front and around. I can put a spray bar low underneath if I need to.

I'd say reducing or messing with flow too much has done it.