I am hoping you can provide some guidance or suggestions. I am having trouble getting good growth on most of my plants. I have a 240g planted tank. I run 3 50w daylight LED floodlights (6000k). I haven't used a par meter, but likely it qualifies as high light, as the tank is two feet deep.
Tank parameters :
Ammonia: 0, Nitrates 5-15 ppm, nitrites 0. TDS currently around 250. The tank gets CO2 (pH is around 6.5 at its peak).
Fertilization was irregular (likely a cause of some of my problems) until about two weeks ago, when I started dosing dry ferts in a manner suggestive of PPS pro dosing levels (i.e. relatively conservative.) I currently dose 7 X a week with a mix of macros and 7X a week with Plantex CSM+B. I used the rotalabutterfly calculator to find an amount that would give me appropriate PPM by day 7. Water changes are typically ~30-50% biweekly. I also have root tabs.
My main issues are twofold : persistent brown algae that coats nearly everything (I think diatoms) as well as strange holes in my Amazon swords and odd growth patterns in my crypts and other plants. Initially I suspected it was a two-fold phosphorus / potassium deficiency along with a photo period that was too high (was 10, lowered it to 7.) But, after trimming damaged leaves away, I am a bit stumped as to why I am seeing the growth I'm seeing still. The amazon swords, for example, seem to melt away down to the veins in a skeleton like pattern, and the crypts seemed to transform to a bizarre hybrid of squat leaves with spindly tops.
I'm sure I'm forgetting something extremely basic, so I'm hoping an expert can whip me into shape. I'll attach photos. Lastly, my soil is Aquariumplants.coms' own brand.
My main goals are :
1. Reduce the stubborn diatoms (the tank is 4 months old) and
2. Get normal looking growth.
Thanks for looking!
Things I see from the images and your description.
First with the questions:
How do you diffuse co2 and what is the flow around the tank, do you get a 1 point PH drop from this CO2 by lights on?
When you say that you translated the rotalabutterfly calculations into PPS pro, why didn't you just use the PPS pro calculation option? Why aren't you dosing standard EI?
Why the biweekly water changes? Assuming once every 2 weeks.
The blackened stem tells me that it's at least in part a CO2 deficiency as that's one of the indicators that I had happen in my aquarium and stopped when I optimized flow.
Judging by the PPS pro you might not be adding enough ferts into the system and if you're dosing phosphates at the same time you're dosing csm+b these nutrients aren't getting to the plants as the phosphates and iron in the csm+b react together when dosed close together. Typical schedule is alternating days for dosage of phosphates and micros.
Assuming you mean you're doing a water change every 2 weeks, this could be one of the reasons why you're having issues. Regular maintenance is required to keep up a healthy tank with high lighting, Co2 and added ferts to keep stuff from building up. Indicators that more frequent maintenance is required in my tanks are when I start to see algae that isn't just caused by high lighting (green algae on the substrate right under the light for example).
I would recommend you tune the CO2 so that there's a 1 point ph drop before lights on. Start dosing a higher dosage of ferts using the standard EI method. Start doing at least a 50% water change every week. Until the tank becomes clean and the plants start responding to the other changes, it might be worth it to do twice a week 50% water changes to reset everything.