Plants failing in 300 gallon tank

[pondholler]

We have a 300-gallon tropical aquarium. The fish are doing fine but the plants are really struggling. Black algae is part of the problem, I'm sure, and we are treating for that, but I am wondering if something else could be going on. Is it possible to have too much light? We have six 4-foot full spectrum LED lights that run from 6 am to 8 pm. Is that too much? Do we need to disconnect some of the lights or shorten the lighted day? Another thought would be heat. Though we have a chiller on the tank, we do not have air conditioning and on summer afternoons the tank sometimes gets as high as 82 degrees. The plants were doing fine several months ago, but now look terrible. And we do fertilize, btw. And test water regularly: Ammonia 0%, Nitrites 0%, Nitrates 30-40%, PH 74. Any advice would be much appreciated.

 

[Essjay]

Your lights are on for 14 hours a day, which is probably the cause of the algae. Fertiliser can also cause algae if you add too much for the plants you have.

Can you tell us what type of plants you have as some plants need stronger light and more fertiliser than others.

 

[Jinx_]

Algae is also caused by poor balance. Light and ferts schedule plays a part in all of this, but even then, algae is still an issue. I still have algae, but this is much closer to the lights.
White and RBG lights are all at 100% intensity.

 

[anewbie]

Do you know the gh and kh. For my aquariums I have the lights on from 8 am to 5 pm BUT i have an hour ramp up/down so full light is from 9 to 4 more so intensity is important here - for my blackwater aquariums i have in general a par around 30 at the substrate with one exception where i'm growin repens with success (I have around 14 blackwater aquariums); for non blackwater aquariums i have a slightly stronger intensity.

I was reluctant to respond because i have had 2 aquariums break out with bba (very heavy dosage across entire aquarium) for reason i don't fully understand. However after about 3 months in one aquarium all the bba died and after about a year it was all gone fallen off in massive amounts. In the 2nd aquarium the bba is mostly dead but hasn't fallen off yet - bba has been a bit of a mystery to me because while i believe it is related to an imbalance the exact imbalance is not well explained or have not fit my environment. I do know it is more prevalent with high co2 and blackwater aquariums inheriently have higher concentration of co2.

For algae there are different types - if any plant gives way or retreat i will get a lot of stringy algae as the plant dies back mostly around or on that plant and it has been very clear the algae is eating off the decaying plant matter or otherwise taking advantage of the plant matter. In truth even my tap water aquariums are soft by a lot of standards with kh 3 gh 6 and tds 120 and i've never dealt with hardwater but with the exception of force co2 injection the #1 mistake i see is too much fertilizer and/or too strong light - hard algae (sometime called spot algae) on the glass is almost always due to too strong light. I also use a minimal amount of fertlizer with heavier usage of root tabs over liquids - the only aquarium i still routinely put in liquid fertilizer is my nurii farm since i'm reluctant to change the environment for these uncommon plants that have done well. However even in that aquarium (which is tap water) I've reduced the light quite a bit without ill-effect.

Last thing to remember is most plants work in order of months so an issue you see today might have been triggered by something you did 4 or 6 weeks ago and changes frequently require 4 to 12 weeks to verify if they work. There are a few exceptions such as a plant starved for nutrients might show immediate growth if you add some root tabs but general adaption take time. I've had folks 'brag' how fast a new plant is growing not realizing that the growth started before they purchased it and are very disappointed when 2 months later they struggle.

None of this is a huge amount of actionable help but you definitely have your lights on too long and are likely using too much fertilizer but futher information would require more precise information on light intensity and water chemistry.

[The reason for gh/kh/ph matter so much is very soft low ph aquariiums can allow the plants to absorb minerals more efficiently as well as increase co2 concentration in the water; also temperature plays a role where as many plants will grow well at 77 or 78 but struggle or die at 83 or 84.]

 

[pondholler]

Your lights are on for 14 hours a day, which is probably the cause of the algae. Fertiliser can also cause algae if you add too much for the plants you have.

Can you tell us what type of plants you have as some plants need stronger light and more fertiliser than others.

I wish I could tell you which plants we have, but I am pretty ignorant when it comes to plant names. For a couple of years, we had lots of water sprite, but it has all died off. We are left with some dark green broad leaf plants, some very tall spikey plants and some low-growing plants that look a little like crabgrass. They are all struggling. About a year ago, we started feeding macro and micro nutrients because the water sprite was dying off. Then we added MORE light thinking that was the issue. Could be our efforts to save the plants were having the opposite effect.

So....how long should the lights be on? And should we fertilize at all? And can you recommend some varieties of plants that are fairly heat-tolerant. (On this July day, it is 87 degrees in the house and 83.7 in the tank with the chiller on -- we can't do better than that). I'm at the point that I'm ready to replace all the plants and do a major water change (we're on a spring) and start over.

Thanks fo your help.

 

[pondholler]

Do you know the gh and kh. For my aquariums I have the lights on from 8 am to 5 pm BUT i have an hour ramp up/down so full light is from 9 to 4 more so intensity is important here - for my blackwater aquariums i have in general a par around 30 at the substrate with one exception where i'm growin repens with success (I have around 14 blackwater aquariums); for non blackwater aquariums i have a slightly stronger intensity.

I was reluctant to respond because i have had 2 aquariums break out with bba (very heavy dosage across entire aquarium) for reason i don't fully understand. However after about 3 months in one aquarium all the bba died and after about a year it was all gone fallen off in massive amounts. In the 2nd aquarium the bba is mostly dead but hasn't fallen off yet - bba has been a bit of a mystery to me because while i believe it is related to an imbalance the exact imbalance is not well explained or have not fit my environment. I do know it is more prevalent with high co2 and blackwater aquariums inheriently have higher concentration of co2.

For algae there are different types - if any plant gives way or retreat i will get a lot of stringy algae as the plant dies back mostly around or on that plant and it has been very clear the algae is eating off the decaying plant matter or otherwise taking advantage of the plant matter. In truth even my tap water aquariums are soft by a lot of standards with kh 3 gh 6 and tds 120 and i've never dealt with hardwater but with the exception of force co2 injection the #1 mistake i see is too much fertilizer and/or too strong light - hard algae (sometime called spot algae) on the glass is almost always due to too strong light. I also use a minimal amount of fertlizer with heavier usage of root tabs over liquids - the only aquarium i still routinely put in liquid fertilizer is my nurii farm since i'm reluctant to change the environment for these uncommon plants that have done well. However even in that aquarium (which is tap water) I've reduced the light quite a bit without ill-effect.

Last thing to remember is most plants work in order of months so an issue you see today might have been triggered by something you did 4 or 6 weeks ago and changes frequently require 4 to 12 weeks to verify if they work. There are a few exceptions such as a plant starved for nutrients might show immediate growth if you add some root tabs but general adaption take time. I've had folks 'brag' how fast a new plant is growing not realizing that the growth started before they purchased it and are very disappointed when 2 months later they struggle.

None of this is a huge amount of actionable help but you definitely have your lights on too long and are likely using too much fertilizer but futher information would require more precise information on light intensity and water chemistry.

[The reason for gh/kh/ph matter so much is very soft low ph aquariiums can allow the plants to absorb minerals more efficiently as well as increase co2 concentration in the water; also temperature plays a role where as many plants will grow well at 77 or 78 but struggle or die at 83 or 84.]

Thanks very much for all the helpful info.

I am embarrassed to admit that I have no idea what the gh and kh are. Please advise.

I had a hunch the lighting might be part of the problem because the plant issue got worse when we added lighting thinking lack of light might be weakening the plants. So you're saying 7 hours of light is plenty, right?

As for the hardness of the water, our tap water comes from a bold spring and the PH is steady at 7.4 -- not soft. Should it be softer? And if so, how do we remedy it.

The heat is another issue. In the fall through spring, our tank keeps a constant 78 degrees, but in the summer it can get as high as 84 even with the chiller working full blast. Are there heat-tolerant plants? If so, what are they?

I am thinking we should replace all the struggling plants, change the lighting and reduce the fertilizer. Or is that changing too many things at once.

Looking forward to your reply. Thanks in advance.

 

[anewbie]

Thanks very much for all the helpful info.

I am embarrassed to admit that I have no idea what the gh and kh are. Please advise.

I had a hunch the lighting might be part of the problem because the plant issue got worse when we added lighting thinking lack of light might be weakening the plants. So you're saying 7 hours of light is plenty, right?

As for the hardness of the water, our tap water comes from a bold spring and the PH is steady at 7.4 -- not soft. Should it be softer? And if so, how do we remedy it.

The heat is another issue. In the fall through spring, our tank keeps a constant 78 degrees, but in the summer it can get as high as 84 even with the chiller working full blast. Are there heat-tolerant plants? If so, what are they?

I am thinking we should replace all the struggling plants, change the lighting and reduce the fertilizer. Or is that changing too many things at once.

Looking forward to your reply. Thanks in advance.

I'm more familiar with plants in very soft acidic environment; having said that yes too much light and too strong light will make things worse as well as too much fertlizer. ph isn't a metric i can work with but if the stable ph is 7.4 then most common softwater plant growth will be slow and you can't change that.

In my discus tank (only aquarium i run at 84); yes a lot of plants that do well at 78 will wither and die or struggle.