[ptownaquariums]

Hi everyone,

I'm wondering why as my plants grow, the older growth turns dark brown but the new growth is light green. I want to reduce or eliminate the amount of dark brown growth from my plants. I am currently running a CO2 system at about 1.5 bps and I have a Beamworks DA FSPEC light 10000K, Actinic 460nm, Red 620nm, and Green 520nm spectrum LEDs. My light is on for 9 hours a day, although I have also tried 8 hours and 10 hours. I have also tried to adjust the distance of the light from the tank, but I haven't noticed much of a difference. I am also adding flourish comprehensive plant supplement and doing water changes regularly. Does anyone have any recommendations on how to prevent the brown spots on the older plant growth? If this is not the result of nutrient deficiency is it from algae blooms? If this is from algae, what can I do to prevent it?

 

[Kubla]

Looks like the brown is alage growing on the leaves. You need your CO2 level in the tank. The 1.5 bps is your rate but doesn't tell us how much CO2 is dissolved in the water. The best way to test is to remove a bit of water. Let it sit and completely degas, usually 24 hours will do. Now test the ph. This is the baseline for your water. You'll want the water in your tank to be about 1 full point of PH drop at full saturation. If your baseline water is 7.4 ph degassed you'll want the ph in the tank to hit about 6.4 after the CO2 has been on for a couple of hours.

You don't state the size of the tank or the distance of the light to the substrate or how much you're dosing.

Flourish comprehensive is not comprehensive and is missing several key nutrients your plants need to grow.

 

[ptownaquariums]

My baseline water is at 7.6 pH degassed and at 6.4 pH when running CO2 in the tank. The size of my tank is 65 gallons and my light is 25 inches from the substrate, although I have previously tried at 18 inches from the substrate.

 

[Tiger15]

Look like brown algae on old growth. Get more algae eaters or dose Excel.

 

[Kubla]

I don't think I would add Excel when you already have over a 1 point PH drop from real CO2. You should take a look at your dosing and nutrient levels. Flourish is not comprehensive plant nutrition. It's basically micros and trace elements. It does not have sufficient levels of the macro elements and depends on other methods to supply them. If that's all your feeding the plants you need to figure out where you nitrogen (N), phosphorus (P) and potassium (K) levels are. One or more of these may not be at a sufficient level for the amount of light you're adding.

 

[Tiger15]

I don't think I would add Excel when you already have over a 1 point PH drop from real CO2. You should take a look at your dosing and nutrient levels. Flourish is not comprehensive plant nutrition. It's basically micros and trace elements. It does not have sufficient levels of the macro elements and depends on other methods to supply them. If that's all your feeding the plants you need to figure out where you nitrogen (N), phosphorus (P) and potassium (K) levels are. One or more of these may not be at a sufficient level for the amount of light you're adding.

Excel is used as an Algaecide that has nothing to do with pH drop. The liquid carbon claim has no proof.

 

[Kubla]

Excel is used as an Algaecide that has nothing to do with pH drop. The liquid carbon claim has no proof.

Excel is typically used as a substitute for injected CO2. The OP already has injected CO2 at a high enough level to get 1+PH drop. I think it would be beneficial for the OP to make sure his dosing is complete (currently not dosing macros!), and in line with the amount of light and CO2 that he's adding. I would do that before adding a highly toxic disinfectant to the tank that at best will be a temporary solution. YMMV.