Help! Hygro has brown spots

CO2

I have a client that called me out to check his tank he'd been doing EI with for a long time. We looked at the dosing log, nothing out of the ordinary.....

The tank was perfect the last few months.

I looked under the tank.........the pump driving the CO2 reactors was unplugged. Apparently the last week's water change had the CO2 system unplugged for cleanign but forgot to switch it back "on".

Opps!

The tank looked pretty good for being a high light packed tank without any added CO2 for a week. Excel is dosed 2x a week, so that likely helped.

But.........back to your issue, the Giant Hygro all had holes on some of the leaves.

I've seen this consistently and many folks think it's K+, however, K+ is added in the form of GH booster and KNO3, to at least 6x what would be required vs N.

So I'd have to use up all the N @ 6x the rate relative K+ before K+ would be an issue............that's not happening.
Stunted tips, browning, rotting etc, species express their dislike for non stable or sudden low CO2 many ways.

I know this plant and several others very well in terms of deficiencies.
Algae, and plants are better test kits once you know and have confirmed the cause.

Regards,
Tom Barr

 

No, this is a CO2 issue, I know this plant, know this deficiency.
Been there, done this, I lost count now.......

I've confirmed this many times.

Regards,
Tom Barr

 

The issue is not from going from one method in a stable tank to the other.
Plants will adapt well.
But rather, switch back and forth between high/low CO2, DIY folks have many issues with that. They bob between high CO2 and low.

That's a big issue.

Plants want stability. Some plants, are very aggressive with getting the CO2, other's grow slower to make up for it, so some may not do well with some plant combos.
This is not allelopathy, it's competition between plants for nutrients(NO3, CO2, light etc). Pruning some back well can help.

You can remove some plants or prune them back a bit and the others will start to grow well.

Regards,
Tom Barr

 

Yep, the plant appears to drop those leaves and eat's the reserves from some leaves, yet leaves soem alone. It takes about a week for the adjustment, up to 3 weeks in some cases.

While the plant needs time to develop, it still needs more RUBISCO, but it need Carbon skeletons to make that.

If carbon is limiting, the time required is longer.

The plant is not N or P or K+ or trace limited though.
The plant likely takes the carbon, the sugars, the starch etc from certain leaves and translocates it to the new shoots/leaves.

I see many new side shoots comiung up when I've done this.

These tend to be resisent to low CO2.
But we already know there's more RUBISCO in leaves grown under low CO2 vs non limiting high CO2.

Regards,
Tom Barr

Regards,
Tom Barr

 

How precisely a plant "choses" to drop and/or sacrifice some leaves, but not others is an interesting topic for plant Biologist.

Generally, non CO2 enriched leaves are smaller, thinner.
, more "ruffely", undulated, pinnate etc.

Mermaid weed looks very different in non CO2 tanks vs the CO2 enriched tanks.

Regards,
tom Barr