PAR, LUX and/or Lumens for a 20G Long

JustAFishServant

Hey all! I've kept planted aquariums for years but only easy species (H. polysperma, egeria, moss, swords, crypt parva, java fern, anubias etc), and with a bit of Flourish they always thrived though I've become increasingly more interested in ferts and proper lighting. Easy Green will fit my needs (Thrive C is more expensive and geared to high light/tech tanks apparently).

Watt measures power usage and is unimportant to plant growth. LUX is similar to lumens so should I measure both? And though important, I don't think I can measure PAR as I can't find it on most LEDs (I want to avoid expensive PAR meters too when I'd simply get info from other experienced aquarists).

I'm planning a 20G Long blackwater for my girl, Val (stunning super red veiltail betta). I want easy, low-light plants like crypts, buce and anubias. I also do "aquaponic" plants like sweet potato, common ivy, chinese evergreen, mint, basil, garlic, purple waffle, dwarf water onion, strawberries, philodendron and pothos but I'm trying to branch out and try medium-light dracaena spp. I use natural sun and what little artificial light they get from my LEDs. So how much PAR, LUX or lumens should I provide a 20 Long, 12" deep blackwater? Do I supplement spot lighting to my "aquaponic" plants or hang LEDs above them?

What confuses me the most is how much PAR, LUX and lumens gets blocked by water. Many LEDs like NICREW provide PAR and LUX readings 12" in air. Is there a way to calculate how much light gets to the bottom of a clear and blackwater setup? Also, what is the point of putting LEDs a few inches above the water. Should I do this also?

Looking for experienced, knowledgeable answers ASAP! Thanks :)
 

Cherryshrimp420

I think lumens is all you need, of course lower wattage would be good too to save energy costs.

With quality LEDs they advertise 1600 - 3600 lumens which should be fine for planted tanks.

A lot of it gets blocked by water, more so if there's tint in the water. I dont think you can grow many plants in blackwater even with strong lighting :(
 

ruud

PAR is dependent on many variables and plants in general have the capacity to adapt somewhat to the spectrum. I would not focus on PAR, unless your ambition is a high tech planted tank. With blackwater, or lets say, a heavily stained tank, I would most definitely forget about PAR and focus only on Lumen. Lux would actually be better. Lux is equivalent to Lumen that is received. But this too is not provided by light suppliers as it is too dependent on variables beyond control of a supplier. So focus on Lumen for your stained tank.

My suggestion would be to double what is approximately required and use a dimmer to adjust according to what works and what is preferred (also personally!); I would always recommend this approach, but especially for stained tanks. So a 20G fairly shallow "blackwater"... let's say 1500 Lumen; then find a RGD LED unit that offers 3000 and use a dimmer to adjust.

In all this, I assume, you are going for the looks of a blackwater tank that does contain soft water. A real blackwater tank is difficult to achieve and a harsh environment for (almost?) any plant species.

As for the emersed part; I can't help you with this (unless I do some research). I work with emersed as well, but these are typically above the LED unit and simply receive light from ambience. I am not sure what cranking up the lumens for your submersed plants would do to the emersed species you mention.
 

MacZ

Is there a way to calculate how much light gets to the bottom of a clear and blackwater setup?
For blackwater the rule of thump applies: Below 10-15cm aquatic plants may exist, but not thrive. I would use floaters, epiphytes or semi-emersed plants. Maybe a Nymphaea. That's pretty much all that's feasable. Sorry.

The biggest problem is, that the tint a. diminishes with waterchanges (unless you add new botanicals, peat or extracts with each waterchange) and b. can generally vary a lot depending on what and how much botanicals/peat you use. That means you would have to adjust all the time.

Another thing to keep in mind: Seeing how you approach this I would bet you're not into algae. Those rarely show up in blackwater, but especially if it's faux blackwater (Please tell us if you are planning just tinted water or real blackwater.) I can tell you, they might bloom in the top 5cm of the water column if you put too strong lights on. If you are planning for real blackwater you can toss the whole thought about the light, the lack of nutrients will then complicate plants that are not absolutely undemanding even more.
 

JustAFishServant

Thanks for the thoughts MacZ, Cherryshrimp420 & ruud. To answer your question Mac, it'll be sort of a mix of faux and real. I've set these kind of tanks up with oak and aspen leaves and my own IAL extract. It'll be filled with twigs and leaves, seed pods if it's a good deal. I add the tannic/other acids for health, tint/mulm for aesthetics. I don't mind algae (I grow it to supplement the goldfish food, sometimes use it in scapes and am getting into algae scrubbers).

Looks like I choose lumens. I like frogbit and dwarf water lettuce. I have thriving pothos in heavy tinted, acidic tanks, might grow those too. My tap water is 6.8 pH (around 6.5 with tannins) which is good for both frogbit and dwarf water lettuce.

This got me thinking, I often see lumens measured in litres so do I measure in litres/gallons or height?
 

ruud

Yes, lumen is typically expressed as #lumen/liter. But this is just an indication. Height has major impact. Stained/tinted water also. Plant species also.

20 gallon = 75 liters * average 20 lumen/liter = 1500 lumen and double this to 3000. Apply a dimmer and see 1) what works, 2) what you personally prefer, and 3) save energy/costs as well.

If your tank really is shallow, you could select units that give off 2000 lumen and again dim accordingly.

As for plant species, I would suggest also certain crypts such as pallidinerva, ciliata and cordata. Again, succes depends on the distance, the tint, the lumen.
 

MacZ

Thanks for the thoughts MacZ, Cherryshrimp420 & ruud. To answer your question Mac, it'll be sort of a mix of faux and real. I've set these kind of tanks up with oak and aspen leaves and my own IAL extract. It'll be filled with twigs and leaves, seed pods if it's a good deal. I add the tannic/other acids for health, tint/mulm for aesthetics. I don't mind algae (I grow it to supplement the goldfish food, sometimes use it in scapes and am getting into algae scrubbers).

Looks like I choose lumens. I like frogbit and dwarf water lettuce. I have thriving pothos in heavy tinted, acidic tanks, might grow those too. My tap water is 6.8 pH (around 6.5 with tannins) which is good for both frogbit and dwarf water lettuce.

This got me thinking, I often see lumens measured in litres so do I measure in litres/gallons or height?
So faux it is. ;)
 

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