Black algae or some kind of black "coating" on plants

[kolossi]

Hi all.

A friend of mine has a 120cm/48" tank, mainly with Cyperus Helferi, Echinodorus Parviflorus and Anacharis.

Most/all of the a covered by a black coarting, it looks like some kind of black algae, although we are not sure if it is algae or anything else?! The black coating starts in patches and covers the entire leaf after a while.
The plants are growing slower, once they are "infected". Additionally some green thread/hair algae appeared on several spots. Stones are also affected..
The black coating appeared after approx 2 month of initial setup. The Tropica soil was used for the tank.

Light is on 2pm - 9pm, CO2 comes one 2h before lights until 8.30pm (2 bps). The amount of CO2 was not increased, since some of the fish (Guppies) start gasping on the surface.
The water is being aerated from 9pm to 11am.
Water conditions appear normal, ph is at 6 (which is the measurable minimum).
Ammonia is 0, Nitrite is 0 and Nitrate is at 100ppm.
GLA ferts ( https://greenleafaquariums.com/products/pps-pro-aquarium-fertilizer-package-bags.html ) and the PPS system are being used on a daily basis.

Anyhow, it seems something is unbalanced, but the question is what exactly is not in balance and how to correct is or what the real issue is ...

Thanks a lot in advance for your help!!

kolossi

 

[Matty123]

Diatoms. Indicative of a few possible causes: immature filter/substrate, too much lighting and or too little/inadequate flow.


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[jkh13]

What filter are you running on that? It's likely a flow issue.

 

[Oksana]

I am using Fluval 406. I thought about the same I might have not enough flow. Now I bought Fluval FX6. Didn’t try it out yet.

 

[jkh13]

I am using Fluval 406. I thought about the same I might have not enough flow. Now I bought Fluval FX6. Didn’t try it out yet.

How many litres are in your tank? You should aim for 10X flow if possible.

 

[Oksana]

How many litres are in your tank? You should aim for 10X flow if possible.

I have 220 liter tank and my filter does around 4 times an hour the entire volume of the tank.

 

[Oksana]

Diatoms. Indicative of a few possible causes: immature filter/substrate, too much lighting and or too little/inadequate flow.


What do you mean with immature substrat? My substrat is from Tropica. Before I had another brand and still had the same issue. A few month after set up I start to see these black coating.
The filter is 8 month old.

 

[Matty123]

That the beneficial bacteria hasn’t populated the substrate yet due to being immature and possibly giving off ammonia... lower the demand (light) which will lower the demand on increasing Co2, flow and additional ferts etc. Light is the main factor here which is the accelerator.


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[Oksana]

That the beneficial bacteria hasn’t populated the substrate yet due to being immature and possibly giving off ammonia... lower the demand (light) which will lower the demand on increasing Co2, flow and additional ferts etc. Light is the main factor here which is the accelerator.


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Ah ok sounds good! I will try it and will let you know. Do you an idea how to determine the output of my light and demand for my tank? I also wanted to add that I have a power head which creates additional flow/current in the tank but no additional filter "turn over", though.