Par vs Run-time - The Planted Tank Forum
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post #1 of 4 (permalink) Old 01-01-2021, 04:01 PM Thread Starter
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Par vs Run-time

Hi All,

I've been playing with my Lighting, Fertilization etc etc etc for the last few months (moved to a new Dosing Method)
60" x 20" x 20" rimless aquarium
No Lid
Fluval FX6 and Fluval 206 filters
Eheim 350 Surface Skimmer
5" of Eco-Complete substrate (Root tabs used)
C02 Injection (Reactor)
3 Ecotech Radion XR15 FW Gen 1 (hung ~8 inches above water line)
Fairly Heavily Planted:
- Background - various stems requiring high and medium light
- MidGround - various stems requiring high and medium light
- Foreground - dwarf hairgrass (not a full carpet), tiger lillies, crypts, anubias, madagascar lace
- Java and Weeping moss on rocks

Although I'm not running into any severe issues, the tank doesn't look great yet as I am battling pesky cyno here and there and a bit of hair algae on some of the stems (which I cut it off when I see it) and also a bit of green spot algae here and there (clearly still working on the fert dosing schedule). As mentioned... I'm playing with both fertilization and lighting changes at the same time (which probably is not smart).

That being said, I am looking for some thoughts/advice from you experts out there regarding light intensity vs runtime.
My question is: How intense vs how long should I run my lights to get the best plant health & color?

I am currently at about 100 PAR for the high light planted sections & 50-70ish for the rest of the tank at the substrate level (I rented a par meter from BRS to do the measurements). I currently have my lights run @ 77% intensity with 100% Red, 80% green, 100% cool white, 20% - 40% blue (depending on the time of day), 0 Royal Blue, 0 UV. I run them at 77% for 7 hours with an additional 1/2 hour ramp up and 1/2 ramp down at both the beginning and end of day

Would you recommend less runtime/higher light or less intensity/longer runtime or the answer just keep playing with it and there is no right answer. I hear light runtimes from anywhere between 5-12 hours.

Very interested in what you all are doing. Want to get this tank perfect. Once I do.... it of course is an excuse to buy another tank...LOL
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post #2 of 4 (permalink) Old 01-02-2021, 12:53 PM
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Its a little difficult without info on water quality parameters or pictures. But Id guess you can knock down your lighting a bit, or maybe change up the balance of color.

I would consider taking red and cool white down a decent bit from 100%, then adjust the others accordingly to your aesthetic preference. Hard to say exactly how much to bring them down....I dont have those lights, but I also dont typically use any lights, or parts of lights at 100%. Maybe shoot for an overall power of 50-60% instead of 77?

Aside from lights, if youre not having decent growth after a month, youve likely got some other things going on. More tank info and pics might help.

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post #3 of 4 (permalink) Old 01-02-2021, 01:55 PM
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As always, there are many variables that go with a planted tank. Just focusing on the lighting, this is what I am doing on my 2 tanks using the Radion XR15 FW Gen2 lighting (1 light on 40g and 2 lights on 75g)

My suggestion would be to start with the numbers in the first picture. This will give you something closer to 80par which will be plenty until your overall tank health improves. With the Gen 1 lights, your software variables and light diodes will be a little different than mine, but this should give you a good start.
If you want to spend some time digging thru a build thread, it would seem my 75g tank is reasonably close to your tank (co2, eco complete, stem plants, etc.).
One thing you did not mention is your water source. Here my tap water is not the greatest - 80+ calcium and fairly high in magnesium. I found that switching to a cleaner water source (i.e. RO water) has made a significant difference for me. It would also seem I am getting better overall plant health using LESS fertilizer.
Also, as one of the other "experts" here would mention, good overall tank health starts with maintenance. The cleaner the tank, the better your chance of having happy plants and less algae.

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post #4 of 4 (permalink) Old 01-03-2021, 12:53 AM Thread Starter
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Thank you!!! I will indeed lower the intensity and use your parameters. Right now using tap water which oddly enough the oh kh and gh are all pretty reasonable at 80ish-100ish, 80-120ish and 6.8ish. Thats if you believe the liquid tests which to be honest I have little faith in. I’m trying to avoid the whole ro water thing if I can. Thanks again. Much appreciated. I’ll let you know how it goes.

Meant to say gh, kh and ph. No ammonia, no nitrites, 20 nitrates, 0 chlorine, 1.0 phosphorus Dont really test anything else.

Last edited by Darkblade48; 01-05-2021 at 02:03 AM. Reason: Please use the edit function for back to back posts to keep threads cleaner
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