# Sooo ..how much PAR do I need for low, med and high light plants



## nicks7.1985 (Aug 11, 2010)

I was looking at Hoppy's charts and can see how much PAR diff distances get with diff lights...but I dont know what plants can grow at what PAR.

Can anyone offer some general guides like ....
low light plants need 20-30 par
med light plants need 30-50 par
high light plants need >50 par ....i just used random numbers for this but you get what im asking.

Thanks a lot!

Nick


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## VeeSe (Apr 16, 2011)

You can grow almost everything with 40-50mmPAR. A lot of plants will grow at 30mmPAR, and 20-40mmPAR would be low light, as you said. You are pretty close with your ranges, but I don't think you are ever forced to go really high due to plant needs. Hoppy also has low, medium, and high light labeled on his chart, but high light plants will grow in medium light as well.


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## nicks7.1985 (Aug 11, 2010)

thanks ..i must have missed that on Hoppy's thread


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## Hoppy (Dec 24, 2005)

What PAR range coincides with high, medium and low light is still a bit indeterminate. I know 20 is good enough low light to grow plants without CO2, but not at all fast. With CO2, it is enough to grow plants reasonably fast. 40 is low medium light, where almost anything will grow if you have good CO2. Above 50 or so, will become an algae heaven if you don't use high concentrations and steady concentrations of CO2, so that must be high light.


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## nicks7.1985 (Aug 11, 2010)

ah ..great , thank hoppy. so pretty much id want to keep it around 40 or so for reasonable growth w/out co2 in a low - mediumlight tank. those charts you did up really help too..cheers!


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## Hoppy (Dec 24, 2005)

Plants grow best when they have enough CO2 available to meet their needs. That is true at all light levels. At lower levels they don't grow as fast, so they don't need as much CO2. But, CO2 is still the best thing you can do for your plants once you have enough light.


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## nicks7.1985 (Aug 11, 2010)

ya ..i wanted a tank that was relatively hastle free..cuz ill be away from home for a while a few times over the next few months
i guess adding lots of fish can work


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## Hoppy (Dec 24, 2005)

My tank is a 65 gallon tank. I use a two bottle CO2 system, http://www.plantedtank.net/forums/showthread.php?t=178503 which requires about 15 minutes of work once a week. Other than that my only tank maintenance is once a week water change, pruning, cleaning, etc. And, I have 10 full size platys, about 10 platys .5 to 1 inch long, and possibly 10 more under 1/4 inch long. It could handle many more easily.

I fertilize once a day, per the EI method, but I could fertilize weekly if I chose to do so, so I could then leave the tank on its own for a few days at a time if I needed to. I fertilize daily just to keep my attention on the tank, and because I can more easily remember that than a 3 times a week schedule, for example.


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## Dave-H (Jul 29, 2010)

It is amazing what you can do with low light + CO2. I have around 9-14 PAR at substrate and lots of lower light plants growing, but also some blyxa and others. I fertilize weekly using a modified EI, and the plants seem pretty happy!


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## nicks7.1985 (Aug 11, 2010)

arrgh ...the diy co2 is a nice idea ...i have a 10lb cylinder, reg,solenoid etc ...i was trying not to use co2 at all. but if i do it will be diy ..just cuz im bored haha.

but if i use diy co2 ,that would mean i have to fert too? (like a modded EI as Dave said)
i kinda didnt want to have to do it everyday.

what are your thoughts on low-medium light ,diy co2 and no ferts ...bad idea?
or do you think it would be safer to just skip the co2 and fertz altogether
or maybe ferts alone? (small..very small amounts)

that said, Hoppy... so you change out the 2 bottles every 2 weeks?


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## Hoppy (Dec 24, 2005)

I change one DIY bottle a week, so the changes are staggered. CO2 makes the plants grow faster, so they need more nutrients to support that growth. Yes, you will probably need to dose fertilzers now, too. With low to low medium light you can probably dose the tank once a week, when you do water changes, and do well enough. If you also put substrate fertilizer capsules in the substrate you can be a lot more relaxed about the fertilizing of the water.


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## nicks7.1985 (Aug 11, 2010)

gotcha Hoppy ... do you think i need substrate capsules even though i used mineralized top soil for my sub? 

If i dose the water column once per week ... how much do you think i should use..like maybe 30% of E.I. recommended?

id like to say i think it is a really neat idea to change the bottle at night so when the lights come on the new bottle would have had time to "catch up"


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## Hoppy (Dec 24, 2005)

MTS should be fertile enough that substrate caps aren't needed. Depending on how much light you have I think I would dose about half of the recommended weekly dosage (3X what the table shows is the weekly dose - about half of that). And, when you do this you just about have to do weekly 50% water changes.


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## nicks7.1985 (Aug 11, 2010)

thanks for the info Hoppy ^^ 
i wanted to get away with not having to do w/c every week... i was planning to use the MTS without co2, little ferts like a once a week dose and w/c once a month or so. i still think it will work to grow healthy low light plants. i realize the plants wont grow at their maximum not given optimum conditions...the goal was to have a slow growing but lush tank with no algae and little maintainence. 

ill start with that , but i have a feeling that within the next week or 2 ill hook up some diy co2..but i'll see how it goes. i really do appreciate the advise you give..it gives me more "ammo"


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## flight50 (Apr 17, 2012)

Make sure you base your water changes based on your fish/plant demands and not based on when you want to do the change. There are several threads on this site as to how much we change the water. The bottom line though, is the water needs to be changed regularly. But like I was saying it depends on your inhabitants and to what tech level of your tank you have setup.


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## biglos201 (Jan 28, 2013)

Hoppy said:


> My tank is a 65 gallon tank. I use a two bottle CO2 system, http://www.plantedtank.net/forums/showthread.php?t=178503 which requires about 15 minutes of work once a week. Other than that my only tank maintenance is once a week water change, pruning, cleaning, etc. And, I have 10 full size platys, about 10 platys .5 to 1 inch long, and possibly 10 more under 1/4 inch long. It could handle many more easily.
> 
> I fertilize once a day, per the EI method, but I could fertilize weekly if I chose to do so, so I could then leave the tank on its own for a few days at a time if I needed to. I fertilize daily just to keep my attention on the tank, and because I can more easily remember that than a 3 times a week schedule, for example.


Hey Hoppy, 

How do you feel about LED Lighting like the Satellite plus? Do you think its sufficient enough for Med light in planted tanks?


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## gus6464 (Dec 19, 2011)

I remember someone on this board with some off the wall numbers for low, med, and high light. If I remember correctly:

low - 0-50 PAR
med - 50-120
high - 120-250

I myself can't even see myself pushing 50 PAR without co2 or excel and I guess all those people with high light plants only pushing 100 PAR are doing it wrong.


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## scx (Sep 8, 2013)

gus6464 said:


> I remember someone on this board with some off the wall numbers for low, med, and high light. If I remember correctly:
> 
> low - 0-50 PAR
> med - 50-120
> ...


That seems really high. I though 50+ is high light


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## gus6464 (Dec 19, 2011)

scx said:


> That seems really high. I though 50+ is high light


It is. I have pushed something like 200 PAR at the substrate of a tank and it's way too much light to manage. Plants grew super fast and I had to dump some serious amount of CO2 into the tank to keep algae from taking over.

That much PAR does help for dry start though as carpets will grow very quickly. If you can push 200-300PAR on a dry start by all means do it as plants will have unlimited amounts of CO2 from the air.


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## biglos201 (Jan 28, 2013)

scx said:


> That seems really high. I though 50+ is high light


It looks like the Current LED Plus is pushing about 28 par at 18inches from the substrate. I guess I might have to use my LED's as well as the T5 to get these new plants to grow?


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## biglos201 (Jan 28, 2013)

gus6464 said:


> It is. I have pushed something like 200 PAR at the substrate of a tank and it's way too much light to manage. Plants grew super fast and I had to dump some serious amount of CO2 into the tank to keep algae from taking over.
> 
> That much PAR does help for dry start though as carpets will grow very quickly. If you can push 200-300PAR on a dry start by all means do it as plants will have unlimited amounts of CO2 from the air.


Great tip, thanks! Maybe I'll acclimate the new plants with the t5 as well as the LED to jump start the growth!


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## Couesfanatic (Sep 28, 2009)

This is from the lighting sticky:

Values between 10-30 are considered low light.
Values between 30-80 are considered medium light.
Values between 80-120 are considered high light.

I'd go with the Current USA satellite plus if I were you


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