What is causing necrosis in my plants?

[Tech Support AN]

To be honest, I don't know at what exact pH you will see all of bicarbs. get converted to CO2 completely. However, from the CO2 charts, which I'm sure you have seen, it shows that at a pH of 6, you have a CO2 concentration of about 15 and a KH of 0.5. So my assumption would be that anything under a pH of 6 is going to be mostly CO2 and/or carbonic acid.

Here are the instructions for the Flourish Tabs:
Insert one Flourish Tab™ in the gravel for every 10–15 cm (4–6 in.) radius. A standard 10 gallon aquarium requires 6 tabs. Distribute the tablets evenly throughout the gravel bed. Push each tablet midway into the gravel bed. Add new tablets once every one to three months for optimal plant growth. Tabs will not alter pH, but, in very soft or unbuffered water, they have slightly acidic properties similar to peat moss.

In my planted tank here at Seachem, I replace the tabs every month and have had great results.
As long as you place the tabs midway into the gravel per instructions, your plants will be able to extract the nutrients, as the tabs begin to dissolve into the substrate and spread their goodness. I do not see any problems with adding potassium chloride, as the chloride content is low. Just be sure not to dose too much and monitor your plants closely.

[LabTest57]

[QUOTE=TechSupport AN;7180]
Here are the instructions for the Flourish Tabs:
A standard 10 gallon aquarium requires 6 tabs.[/QUOTE]

So for a 160 gallon aquarium. I need 16 times 6 tabs = 96? I don't think I can fit so many at once...

[Tech Support AN]

You do not necessarily need that many tabs, as it not only depends on the number of gallons, but the dimensions of your tank as well. Just put as many tabs as you can fit throughout the substrate and you will see good results.

[LabTest57]

I was experimenting with my plants by taking some out of the substrate and keeping some in the substrate, while using Flourish tabs. Oddly, the Flourish tabs did not make any improvement in one week, what made an improvement was removing my plants from the substrate for one week. Since my substrate is 3.5 inches deep, could this mean that anaerobic bacteria may have been colonizing a lot and have been disrupting the roots of my plants in some way?

I knew for fact the up-rooted plants (taken out of substrate) would worsen, however, I just wanted be sure it was either nutrient deficiency or something plaguing the inside of my substrate. Some of my plants' roots smells rotten, but the plants haven't died "completely", yet. :(

[Tech Support LK]

It is possible that the buildup of hydrogen sulfide in the substrate could have been affecting the plants. Do you see dark spots if you look from underneath the aquarium? Do you see any other signs of H2S build-up? If so, you may consider siphon cleaning the gravel to remove excess hydrogen sulfide.

[LabTest57]

Yup, I see some dark spots. Though, I always wondered if it was some sort of black algae growing in that darkness. The bottom of the aquarium has some thick pockets of detritus, too. I think I might kill my fish if I disturb the substrate when I siphon it as it may release more hydrogen sulfide, or rotten organics that may cause fungus to grow in the water column. However, doing some research on types of gravels that can contain (build up) hydrogen sulfide, I found out that my gravel-type doesn't pose any risk towards hydrogen sulfide build-up because it has pebbles big enough (big as a 1 gram vitamin C pill) to allow water to filter through. I wanted the substrate to be at that depth, so that it can house a lot of anaerobic bacteria.

Here are some other signs developing on my rooted (in substrate) amazon sword plants:

1) dark spots on leaves and small holes apppearing on green leaves.
2) Green leaves start to brown-up at tip and become yellow at mid-region
3) younger leaves show stunted growth and pale coloring (very-very light green)

[Tech Support LK]

Do you have any pictures of the plants that you could post or send to us? This may give us a better idea in order to try to diagnose.

[LabTest57]

Here you go, one Amazon sword plant with necrosis:

The plant may not look so bad because, all the brown leaves (4) had already decomposed in the water column...

[Tech Support LK]

Looks like an iron deficiency to me. I'd give the Flourish Tabs a little while longer before you count them out.

[LabTest57]

Isn't Iron a micro nutrient, which isn't needed in large amounts? How can a plant have necrosis from an iron deficiency, I thought chlorosis can be the only problem?