phosphorus deficiency.... i think

[Aron78]

Hey Monster Fish People
Check my pics and let me know your thoughts on what might be happening to my Alternanthera reineckii pink.
This is a 20gal low tech tank, borderline fully stocked/over stocked, weekly 1/3rd water changes and dosing with flourish excel. My lighting is 15w which I can't do anything about because of the fitted hood. It does sit by a window with about 1hr of direct sunlight. I don't test the water mainly because when I did I was chasing small problems and causing bigger problems, and really, with weekly water changes everything seems good.... except this Alternanthera reineckii pink. I have java moss and a hygrophila in there as well. Java moss isn't affected at all and the hygrophila is barely affected.
After some research I'm thinking this is a phosphorous deficiency. What do you all think?
Thanks in advance

 

[Beetlebug515]

First off, welcome to the forum! It is certainly a nutrient deficiency. Java moss and most hygrophylia will survive in just about any conditions. The reineckii, not quite the same. They are a much more demanding plant. More demanding plants need to be given the full range of nutrients as well as decent lighting. These nutrients include nitrogen, phosphorus, iron, potassium, co2, and trace elements. For now, I would go with phosphorus, potassium, and iron if I were you. Doses following the manufacturer instructions should clear up the problem. Additionally, you need to test your water. If your tank is overstocked, 30% weekly water changes are likely not enough. The plants won't really help with the nitrate levels if they are not fed and lit well.

 

[Aron78]

First off, welcome to the forum! It is certainly a nutrient deficiency. Java moss and most hygrophylia will survive in just about any conditions. The reineckii, not quite the same. They are a much more demanding plant. More demanding plants need to be given the full range of nutrients as well as decent lighting. These nutrients include nitrogen, phosphorus, iron, potassium, co2, and trace elements. For now, I would go with phosphorus, potassium, and iron if I were you. Doses following the manufacturer instructions should clear up the problem. Additionally, you need to test your water. If your tank is overstocked, 30% weekly water changes are likely not enough. The plants won't really help with the nitrate levels if they are not fed and lit well.

Thanks BeetleBug
This tank is nearing overstocked but not quite there. Last week I did about 75% water change and it seemed to have sped up the problem! The Reineckii was the first plant in the tank and did really well. I started adding a large bush of java moss and cuttings of hygro. The Java moss hasn't done much since but the hygro really took off but, seems to be at the reineckii's expense. Now the hygro is beginning to show signs of the same problem. I have no noticeable signs of algae growth and figured my nitrates were in check. Will pick up the phosphorus, potassium and iron today and see how that goes. Lighting not much I can do but to wait for the glorious rays of summer to return.

 

[Beetlebug515]

Algae don't rely solely on nitrates for growth. Most forms of algae also rely on phosphorus, silicate, and other plant friendly nutrients. You know your tank is lacking those nutrients, so algae is not going to grow. Nitrates are only one piece of the puzzle.