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Discussion Starter · #1 ·
Hi all,

I am trying to bring my 10 year old tank back to respectable, low tech shape from years of neglect. Things are mostly cleaned up, and the tank is basically algae free and also growing negligible amounts of new algae, which is great, but the problem is that many of my plants are showing deficiencies. Suspecting a CO2 deficiency but not wanting to add pressurized CO2 (I ran this up until ~6 years ago on this tank, but I just don't want to go that route again for maintenance and upkeep purposes), I'm trying to gauge if I'm going too low on lighting. Details below:

Details
  • Tank: is a standard 55G
  • CO2 supplementation: None
  • Plants: Anubias, crypt wendtii, tiger lotus, vals, a few swords, Brazilian pennywort, dwarf water lettuce. Out of all of these, the only one that is growing well is the red tiger lotus, which is showing rapid growth. The pennywort has stunted growth, and the anubias and swords have large holes appearing on new growth.
  • Lighting: one T5HO bulb w/ reflectors in the Aquaticlife T5HO fixture 28" above the substrate with a glass lid in between. (Yes, I know I should move to LEDs, but all my stuff is 10 years old at this point, so the equipment is a bit dated)
  • Photoperiod: Lights are on for a continuous 7 hours a day
  • PAR estimate: Hoppy's old chart from this thread estimates that the 4 bulb Aquaticlife fixture produced ~80 mm PAR at 28", so if I take 25% of that, that would be 20 mm PAR
Since my light isn't dimmable and I have no easy way to raise it more above the tank, I added a layer of window screen in between, which has very noticeably dimmed the light. Hoppy's previous tests have shown that this is likely reduces the PAR by 30-40%, which would put me at 10-15 mm PAR if all the estimates are roughly accurate. This seems a bit low. Am I going too low here? I haven't ever used a PAR meter, so I don't have an "eye test" for what different PAR levels look like.

Thanks for the help to those who take the time to read/respond!
 

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I have a feeling it might be too low. I went too low a couple of times and was forced to get it right. Do you think the 20 PAR is too much? I guess that's what you're saying by detailing the plant deficiencies. So too much light without enough CO2 to make it work? I have two ideas that are probably pretty stupid. One is to put in just the right amount of floating plants for shading. Two is to take the cover glass to a tinting place to have it tinted a little. A low-tech tank is on my list of things to do in life. I think it would be a learning experience.
 

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Discussion Starter · #3 ·
I have a feeling it might be too low. I went too low a couple of times and was forced to get it right. Do you think the 20 PAR is too much? I guess that's what you're saying by detailing the plant deficiencies. So too much light without enough CO2 to make it work? I have two ideas that are probably pretty stupid. One is to put in just the right amount of floating plants for shading. Two is to take the cover glass to a tinting place to have it tinted a little. A low-tech tank is on my list of things to do in life. I think it would be a learning experience.
Yeah, they are good ideas. I could also lower the light back down to be more like 20" above the substrate but keep the window screen. I like the floater idea more actually and am trying to do that myself. The problem is that I've added a few dwarf water lettuce 3 months ago to the tank, but they seem to die at the same rate at which they multiply, which likely signals some kind of nutrient deficiency problem despite me dosing pretty high levels of ferts (like halfway to high tech EI amounts with root tabs next to all the heavy root feeders) in the tank and adding extra Ca and Mg as well. Not sure what exactly is going on since they shouldn't be CO2, nutrient, or light limited.
 

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Hi all,

I am trying to bring my 10 year old tank back to respectable, low tech shape from years of neglect. Things are mostly cleaned up, and the tank is basically algae free and also growing negligible amounts of new algae, which is great, but the problem is that many of my plants are showing deficiencies. Suspecting a CO2 deficiency but not wanting to add pressurized CO2 (I ran this up until ~6 years ago on this tank, but I just don't want to go that route again for maintenance and upkeep purposes), I'm trying to gauge if I'm going too low on lighting. Details below:

Details
  • Tank: is a standard 55G
  • CO2 supplementation: None
  • Plants: Anubias, crypt wendtii, tiger lotus, vals, a few swords, Brazilian pennywort, dwarf water lettuce. Out of all of these, the only one that is growing well is the red tiger lotus, which is showing rapid growth. The pennywort has stunted growth, and the anubias and swords have large holes appearing on new growth.
  • Lighting: one T5HO bulb w/ reflectors in the Aquaticlife T5HO fixture 28" above the substrate with a glass lid in between. (Yes, I know I should move to LEDs, but all my stuff is 10 years old at this point, so the equipment is a bit dated)
  • Photoperiod: Lights are on for a continuous 7 hours a day
  • PAR estimate: Hoppy's old chart from this thread estimates that the 4 bulb Aquaticlife fixture produced ~80 mm PAR at 28", so if I take 25% of that, that would be 20 mm PAR
Since my light isn't dimmable and I have no easy way to raise it more above the tank, I added a layer of window screen in between, which has very noticeably dimmed the light. Hoppy's previous tests have shown that this is likely reduces the PAR by 30-40%, which would put me at 10-15 mm PAR if all the estimates are roughly accurate. This seems a bit low. Am I going too low here? I haven't ever used a PAR meter, so I don't have an "eye test" for what different PAR levels look like.

Thanks for the help to those who take the time to read/respond!
First I don't think I'm very good at guesstimating t5's but I think that at your height Hoppys calcs don't really apply.
Most fixtures were very close to the tank top allowing the light to be trained into the tank w/ glass reflections and water refraction.

Assuming you don't have a bare bottom and about 2" of substrate. My 55" is about 20" in height.
So effective distance is 18" meaning your light is 10" off the top of the tank.
This could cause significant light loss right off the bat.
Say even 10%
Another 5-10% for the glass.
Screen 30-40%

45-60% light loss from 20 PAR..
assuming 20 par initially.
Depending on the reflectors and using Hoppys charts your initial par under normal circumstances could be anywhere from 10-40 PAR.

As a sort of "test" take a piece of cardboard or wood (say 4" x 24"(or longer) and cover it w/ something white. Paper, paint ect.
Put it perp. to the length and on the top and see how far the light "spills" outside the tank. Only need to see one side.
This will give a visual as to how much light isn't even making it into the tank.
 

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Yeah, they are good ideas. I could also lower the light back down to be more like 20" above the substrate but keep the window screen. I like the floater idea more actually and am trying to do that myself. The problem is that I've added a few dwarf water lettuce 3 months ago to the tank, but they seem to die at the same rate at which they multiply, which likely signals some kind of nutrient deficiency problem despite me dosing pretty high levels of ferts (like halfway to high tech EI amounts with root tabs next to all the heavy root feeders) in the tank and adding extra Ca and Mg as well. Not sure what exactly is going on since they shouldn't be CO2, nutrient, or light limited.
I wonder what the low-tech people do when they troubleshoot? I mean how much can there be to it? Maybe it's just the subtle art of leaving things alone most of the time. This sounds like one of the times when you have to do something.
 

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I wonder what the low-tech people do when they troubleshoot? I mean how much can there be to it? Maybe it's just the subtle art of leaving things alone most of the time. This sounds like one of the times when you have to do something.
It's a test in patience and micro managing everything. "Low tech" has been one of the hardest things I've done. "No tech" is very simple in and of itself (failures happen often in set up, but once that's done most of your work is done). "High tech" has a lot of working components but adequate testing supplies and numerous calculators make dialing in and setting relatively simple. "Low tech" has a blend of the 2 but without the simplification afterwards that the other 2 means have. These are just my observations from running these 3 types of planted tanks.
 

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Discussion Starter · #7 · (Edited)
OK, I just downloaded a PAR meter app and saw that post-screen, pre-lid, and about 10" below the light, I was getting 70 mm PAR at the center of the tank. There is a pretty steep dropoff towards the sides of the tank due to the light bulb ending (~40 mm PAR at the ends). I didn't stick my phone into the water for obvious reasons to get a read down at the bottom of the tank, but from extrapolating one of Hoppy's curves which starts at 70 mm PAR at 10 inches (the Coralife dual bulb T5HO line), this puts me at about 15 mm PAR at the bottom in the center, with maybe 8-10 mm PAR at the very ends of the tank. So it seems like the approximations were roughly correct. I'm sure it's not the most accurate PAR meter, but I also think it's likely in the ballpark, and we don't really need it to be super precise for these purposes.

Edit: If I really feel the need, I can take the light off the tank and measure the PAR under the screen 28" away to get a rough assessment, but not entirely sure that's necessary. I'm pretty confident I'm getting 10-15 mm PAR at the bottom of the tank now.
 

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OK, I just downloaded a PAR meter app and saw that post-screen, pre-lid, and about 10" below the light, I was getting 70 mm PAR at the center of the tank. There is a pretty steep dropoff towards the sides of the tank due to the light bulb ending (~40 mm PAR at the ends). I didn't stick my phone into the water for obvious reasons to get a read down at the bottom of the tank, but from extrapolating one of Hoppy's curves which starts at 70 mm PAR at 10 inches (the Coralife dual bulb T5HO line), this puts me at about 15 mm PAR at the bottom in the center, with maybe 8-10 mm PAR at the very ends of the tank. So it seems like the approximations were roughly correct. I'm sure it's not the most accurate PAR meter, but I also think it's likely in the ballpark, and we don't really need it to be super precise for these purposes.

Edit: If I really feel the need, I can take the light off the tank and measure the PAR under the screen 28" away to get a rough assessment, but not entirely sure that's necessary. I'm pretty confident I'm getting 10-15 mm PAR at the bottom of the tank now.
That's about what you expected. What about cutting the screen to allow more light to get to the edges?
 
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