Deficiency sign I can't figure out

Hi all,

The older leaves on my Brazilian Pennywort turn yellowish around the edges, curl downwards, then start to disintigrate. I see a few small brown spots on my sword plant(new leaves), but other than that, there doesn't appear to be any others.

My tank is a 55g with 54 watts of t-5 which I reduced last month from 10 to 8.5 hours/day. I dose flourish recommended dosage and was dosing weekly 1/4 tsp kno3 and 1/8 kh2po4. From all I've read, lack of potassium is what people think is the culprit, so I've dosed 1/4 tsp of both last 3 weeks, but doesn't seem to be any better at all.

This unsightly problem with my pennywort has been consistent through all the changes and progress I've made over the months. It refuses to go away! If I could solve this problem, it would be a major thing for me. Does anyone have any ideas? It would be greatly appreciated.

Thankyou.

 

I'm following Tom's low tech recommendations. I don't add any co2 or perform any (scheduled) water changes.

 

Hi Vaughn,

Just yesterday, I did raise my light one notch (about 3/4") higher and I also reduced my photoperiod from 8.5 to 8 hours. I'm now convinced my powerful light was creating the imbalance/deficiency. I hope this reduction in intensity and duration will allow me to find success without having to add co2. We'll see...

I had to laugh at myself...It's amazing how easy it is to miss all the evidence pointing to one conclusion if you're not inclined to think in that direction. I saw a big improvement in spot algae when light was reduced and I had read an article multiple times stating that these plants do "better" with co2. I've adjusted my dosing amounts without any improvement. I also had read posts by you and others discussing the intensity of t5 bulbs, yet it was shoggoth asking me about co2 before it all came together. Amazing! I had read so often that 1 wpg was sooo low, it took alot to convince me light was the problem.

Thankyou...

Trivr

 

Vaughn,

If you could elaborate on that for me also. I can't seem to find the discussion you and others had on light intensity. My question is intensity vs. duration. Or if you could just provide the link for me.

Thanks.