I ordered a 24" Finnex Stingray for my new 20 gallon high tank and I have been seeing decent results from the swords and Corkscrew Val I put in there. However, the substrate is around three inches deep at the lowest point and about six at the highest which puts the light at about 16" from the lowest point in the substrate. Referencing the par chart for the Stingray this is about 25 PAR at the lowest point which is well within 20-30 PAR at the substrate for low tech. Now I want to replace the dual T5 NO for my 55 gallon long primary tank which is suspended 20" above the substrate. The PAR chart for the Stingray indicates that this would be about 20 PAR which is at the lower limit for low tech PAR. I have been looking at lights for a long time since I realized that spending more for an LED fixture would pay for itself in only a few years. I have narrowed it down to either a Planted + or a Stingray but research indicates that the PAR of a Planted + would be about 50-55 PAR at 20" from the substrate so it is too much despite the posts I have seen recommending Planted + lights for low tech builds. Hanging the light higher isn't really an option as the tank is in the living room and at the current height the rim of the tank blocks the bottom of the light fixture from view at sitting angle.
I know a lot of people on this forum are using Stingrays for their low tech tanks so somebody must be using one on a 55 long or similar tank--maybe dual Stingrays on a 75 gallon. All the PAR data is a great way to do comparison shopping but sometimes it is difficult to connect to real world application and what people are using successfully. And apologies for another lighting question; I know everybody gets real tired of them.