Leaves turning black

[strohl71]

Hello -

I was wondering if somebody with more planted tank experience than me could answer a question.

I have a planted tank with several species of plants but primarily anubias and sword plants. Some of the leaves on these anubias and sword plants are turning a mottled / marbled black. Some leaves are still primarily green but others are getting close to being all black.

I have checked some of my aquarium books but have found no information. What is causing this? Do I have a surplus or a lack of a particular nutrient (iron, phospate, etc.)? What can I do to bring my plants back to a healthy green?

 

[WuddyWoodpeckah]

I read somewhere that excess phosphates can do that. How does your maintenance schedule look like? Maybe a couple of water changes will help.

Sometimes plants also do that if changed from emersed to submersed growth.

 

[chris1932]

I agree with Sandi but I have a few points of my own. Look at a section of the rootmass are the roots white and growing or have they turned brown and soft. Plants absorb most of their nutrients from the root mass. Brownish leaf stems close to the root mass is a sign of potasium deficency, brown dark spots on the leaves lack of iron, slow growth is a lack of light or Co2.
What type of substrate do you have?
How are you adding nutrients?
How big is the tank?
Watts per gallon?
Light temp of bulbs
Hours of light per day?
Is this a sudden thing?
If you have Po4 problems changing water may or may not reduce it, I have seen where source water is the major contributor of Po4. Test your source water, tank water, and food. Some foods are also a large contributor of Po4.

A picture of the tank and plants even if it isnt the greatest would be a big help.

 

[strohl71]

I agree with Sandi but I have a few points of my own. Look at a section of the rootmass are the roots white and growing or have they turned brown and soft. Plants absorb most of their nutrients from the root mass. Brownish leaf stems close to the root mass is a sign of potasium deficency, brown dark spots on the leaves lack of iron, slow growth is a lack of light or Co2.
What type of substrate do you have?
How are you adding nutrients?
How big is the tank?
Watts per gallon?
Light temp of bulbs
Hours of light per day?
Is this a sudden thing?
If you have Po4 problems changing water may or may not reduce it, I have seen where source water is the major contributor of Po4. Test your source water, tank water, and food. Some foods are also a large contributor of Po4.

A picture of the tank and plants even if it isnt the greatest would be a big help.

Thanks for responding. Hopefully I can answer your questions and give additional information.

My tank is 38 U.S. gallon
Tank currently has 4 apistos, about 15 cardinals, 1 ancistrus pleco, 3 oto cats
Substrate is typical aquarium pea gravel.

I was running a triple fluorescent t-8 canopy but it broke about 2 weeks ago. I replaced it with a double t-5 HO (39 watts per bulb). One Life Glo 2 and one Power Glo. It sits on top of my glass top. I guess that gives me a little over 2 HO watts per gallon.

I do not use my house water for water changes as I am on a private well with very high iron content. I use store bought reverse osmosis distilled water.

I do a 25% water change every 3-4 weeks and add a t-spoon of Kent RO Right. I also typically add about 10 ml of Stress Zyme for added bacteria and a capful of Flourish Comprehensive Plant Supplement.

Twice a week I add a capful of Flourish Excel Carbon supplement (I do not have any direct inject CO2 system).

I have to admit my water testing is primitive. I do not have a fancy test kit. I only use 5 in 1 test strips. They do not include phospate in this strip.

I was running my lights for 12 hours per day with a 2 hour siesta in the middle. I just recently adjusted my timer to have the lights on for 10 hours (still keeping the 2 hour siesta in the middle).

The leaves turning black is not a sudden thing. It has been happening for many months. However, it has become quite apparent that it is getting worse and not better.

Hope this helps. Any additional advice is appreciated from either or both of the posters that responded to me. I will attempt to post a pic as well.

 

[ed seeley]

Your plants are short of the things they need to grow and are using the nutrients they do have, in their older leaves to try and grow some new ones! They need more carbon and nutrients. You have a pretty low stocking level so there won't be much nitrate or phosphate for the plants to utilise and you may need to add some once you get the plants growing well.

Personally I'd look at your weekly Excel dose and add part of it daily as gluteraldehyde (the active part in it) only persists in water for about 24 hours. This means your plants are getting bursts of carbon, then nothing for a few days, then another burst - not ideal as plants can't store carbon to use later. Personally when I dosed Easycarbo (the same thing as Excel from another company) I added 2ml per 50l daily.

With 2W of TS per gallon I'd really look at getting a pressurised CO2 set up soon if you can. While they can be expensive to set up refills aren't usually too expensive and they are hassle free! You can always get a regulator and use Carbon dioxide fire extinguishers which are often cheap to get on somewhere like Ebay.

 

[strohl71]

Your plants are short of the things they need to grow and are using the nutrients they do have, in their older leaves to try and grow some new ones! They need more carbon and nutrients. You have a pretty low stocking level so there won't be much nitrate or phosphate for the plants to utilise and you may need to add some once you get the plants growing well.

Personally I'd look at your weekly Excel dose and add part of it daily as gluteraldehyde (the active part in it) only persists in water for about 24 hours. This means your plants are getting bursts of carbon, then nothing for a few days, then another burst - not ideal as plants can't store carbon to use later. Personally when I dosed Easycarbo (the same thing as Excel from another company) I added 2ml per 50l daily.

With 2W of TS per gallon I'd really look at getting a pressurised CO2 set up soon if you can. While they can be expensive to set up refills aren't usually too expensive and they are hassle free! You can always get a regulator and use Carbon dioxide fire extinguishers which are often cheap to get on somewhere like Ebay.

Thanks to all that responded. I will start using Flourish excel carbon supplement on a daily basis and see if that makes a difference. I will also start adding some trace elements from flourish.