What could have cause this rotala plant stem turn black? The black portion will melt off into 2 parts in the later stage but the plant is still surviving. Anyone come across this?

Hi,
Poor CO2 is a likely culprit. Degeneration of plant tissue is normally associated with poor CO2 as a primary cause but could be exacerbated by other factors such as poor nitrates. Try increasing your injection rate if this is an injected tank. If this is a non-injected tank then you may have to lower the lighting or consider adding a CO2 supplement such as Excel.

Cheers,

Hi,

I used to have this issue with Rotala and Ludwigia.

Since I starting injecting additional c02, this issue no longer arises in my tank.
Anecdotal evidence, yes, but supports ceg4048's reply.

However, I do agree that c02 is the likely culprit, regardless of my own experience.

Thanks guy. Although i can see that my CO2 indicator is showing sufficient(i'm using 4dKH solution), maybe it is not dissolving well inside the tank. It could be the reason. It appear only on rotala plant only, kind of strange.

This is the tank i'm mentioning, could it be the plant is too closed to each other? Too compact? Is a 1.5ft cube infront curve tank.



Btw the pic took is not yet CO2 injection, so the CO2 indicator colour is in dark green. I read from "badmanstropicalfish" said that too much phosphate can cause black portion to leaves and so, could it be the culprit?

Yes, that is a distinct possibility. As the plants become bushier this has a tendency to block flow so that the distribution of nutrients and CO2 becomes more difficult.


Nope, that's a distinct impossibility. Phosphorous is a critical element sought out in desperation by all plants. This is what happens to a plant when it encounters too much Phosphate:



Add more CO2 mate.

Cheers,

Thanks! So should i put the rainbar at bottom and behind to distribute the flow. Stem plants get bushy easily after few trimmed, how do we solve this, getting the flow of CO2 and nutrients distribute to them?

Well, you can play with the bar location to see what works but usually the penalty at odd locations is aesthetics. One way is to use filters which have a very high throughput, or to supplement the filter flow with powerheads to get better circulation. I normally opt for the stronger filtration method as it's less obtrusive. In a small tank you can easily use a filter that has a rating of 10X to 20X the tank volume per hour turnover rate. George Farmer does this on all of his small tanks to excellent effect. You do still need to prune regularly though, but a high flow and high injection rate helps you to avoid a lot of the deterioration.

One thing to remember also is that as the plant biomass increases so does the requirement for more CO2 and nutrients, so if you don't adjust the injection rate as more mass is created then less CO2 is available per unit mass. I would first try simply increasing the injection rate for a few weeks first, then think about higher flow if results aren't satisfactory.

Cheers,

Thanks alot for the quick reply! Wouldn't high flow rate causes TURBULENT, plants will be sway everywhere and also causes stress to fauna. Maybe thats the only way to get CO2 and nutrients to the plant bed.

Does temperature affect the plants growth and look, said 28-30 degree celsius, i notice those tanks with chiller the plants look much nicer at around 25 degree Celsius than those at 28-30 degree celsius. Thanks!

Hi,

Turbulence is not a bad thing. The fish like to swim against currents and will go to a quieter place to rest.

Aquatic plants are BUILT to go with the current, so swaying is not an issue for them.

If the fish are clinging to rocks with their fins for dear life 24/7 and cannot rest, then the flow is too much.

Yes, good flow is the only way to get through thick plant beds........

You want to be able to see each leaf move. Think gently swaying........if current moves over the leaf, nutrients are carried TO IT, and NH4 and dirt, etc are WASHED OFF.

More plant species occur in warmer waters than cooler ones, esp the species we keep, so warmer temps are not an inhibitor to plant growth.

Also folks keep discus and plants, and discus require these warmer temps you mention.

As long as the plants are healthy and get good nutrients and light, etc, the warmer temps should not be an issue.