I am at a loss for my current nutrient deficiency issues in my 100G. I am dosing 1tsp of KNO3, 1 tsp of K2SO4, 1/tsp of K2PO4 and 1/2 tsp of CSM+B each 3X per week. I also dose Excel daily. My substrate is a mix of Flourite and Eco-Complete, Lighting is 260watts Coralife PC. Bulbs are a little less than a year old. I use Rootmedic Complete substrate ferts around the swords. But I am still getting browning tips which recede down the leaf on my swords.
I do have 4 BN Plecos, and 5 L010A cats which I had originally thought may be damaging the leaves but they are all extremely plump and Im sure all of the leaf damage isnt due to them. This is primarily associated with the older leaves.
You very likely have very low light intensity, depending on the quality and design of the reflectors in the light fixture. If so, the sword plants would be unable to grow much or very fast. And, you would have to be sure to do 50% water changes weekly to avoid some really high levels of nitrates and phosphates. It isn't at all likely that you have high light.
I think lighting may be an issue, I am using 2x130watt Coralife PCs. I am thinking about upgrading within the next few months to a HOT5 fixture. The tank just looks somewhat dark. With the number of plants I have packed in there I guess it isnt a surprise nutrients and lighting are an issue. My nitrates are also never above 10ppm with the dosing, phosphate is also not measurable. I do have a ton of plants so I guess that helps.
What bulb fixture would you recommend, I figure a 2-3x54watt would be alright? Im not injecting CO2 nor do I plan to do any more than Excel if that helps.
First, nitrate and phosphate test kits have to be calibrated or the readings you get mean nothing. If you are dosing the amount of phosphate you mentioned, with the light you have, it is only barely possible that there is zero phosphate in the tank.
I don't know the dimensions of your 100 gallon tank, but if it is a typical 24 inches high, each pair of T5HO bulbs, with typical T5HO reflectors, will give you high light over at least a foot of the front to back depth of the substrate. It is hard to see a need for 3 bulb fixtures or more than two 2 bulb fixtures. A 4 bulb fixture hanging about 32 inches above the substrate should give you high light over the entire substrate.
But, high light is not a desirable condition, unless you really enjoy doing tank maintenance, adjusting the CO2 system to get the maximum amount into the water without harming the fish, pruning plants twice a week, etc. Much easier to handle, and more fun, generally, is low to low medium light. For that a single 3 bulb fixture hanging about 34-36 inches above the substrate would do it, or 2 one bulb fixtures sitting on top of the tank, one near the front of the tank and one near the back of the tank.
It is very possible my test kit is wrong as it is just an API. Do you think 1 2x54watt HOT5along the back of the tank where most of the plant life is and one 2x65watt PC along the front of the tank would be sufficient? the tank is 48"Lx20"Wx24"T, I have 3" of substrate in the back and 2" in the front.
I will cut back on my phosphate dosing, 1/4tsp enough you think?
With the lights you now have I think I would dose once a week, and I would use double the EI dosages for a 40-60 gallon tank. If you go the the lighting you mentioned - 2 x T5HO at the back and a PC fixture at the front, you would have high light at the back, and probably medium or less near the front. Then I would dose 2 x the EI dosage for a 40-60 gallon tank, 3 times a week. Most important, you will need pressurized CO2 with that much light.