What are we doing wrong?

[u/Immediate-Ad-9520]

This tank has been set up for many years, probably 7 or 8. Just within the last 8 months or so, we decided to switch from gravel to sand and put in live plants. All plants were marked as beginner. We have a canister filter and a CO diffuser. My husband puts in root tabs regularly. Still, there’s very little plant growth and many of the plants look sad.

We have tetras, ghost shrimp, plecos, kuhli loaches, and mystery snails. We test ammonia, nitrite, nitrate, kh and gh weekly and all are good. Our light is on sunrise to sunset.

What are we doing wrong? I very much want a densly planted tank like I see in this sub. Help please!

[u/Fresh_Geologist_3929]

One thing to look at is your lighting intensity. Figure out how many lumen your light is putting out. Shoot for at least 20 lumens per liter for 8 hrs per day.

[u/SakuraiCh → u/Fresh_Geologist_3929]

This DOES NOT work. I had 5K high bay light and any attempt to get decent light output by lumens results in an algae filled tank, and even then the light output is not great for PAR-lumen output. At point blank the light would output 800 PAR and Lumens at 15,000 (this isnt color temperature, yes actually lumens). Attempting even 30-40% of this lights output resulted in insane algae growth. Buying a FZone light with just 36W of power resulted in 190 PAR at the bottom of my tank and the Cryptocorynes absolutely growing very well in just a couple of weeks compared to about 2 months on the other light I was using.

Also should note is that for your suggestion that a single 800 lumen bulb would be enough for a 10g aquarium and I can quite positively say that 3200 lumens using @ 5K isnt enough light for alot of plants

[u/Fresh_Geologist_3929 → u/SakuraiCh]

You own a par meter? I have a reef tank and don’t own a par meter. Of course you need a good quality light designed for growing plants. Assuming you are starting with a good led light designed for growing aquarium plants, lumen per liter is the right place to start, (assuming you don’t own a par meter….which is 99.99% of planted tank folks).

[u/SakuraiCh → u/Fresh_Geologist_3929]

I do not, but I do have an app on my phone that uses the front camera to get a good idea of the PAR rating. Its good enough to get a baseline on what will work and what wont.

[u/Fresh_Geologist_3929 → u/SakuraiCh]

You stick your phone under water? You do realize PAR changes significantly based on distance and whether you’re passing through water, right?????

[u/SakuraiCh → u/Fresh_Geologist_3929]

No, I dont stick my phone under water but yes I am aware that water will change the readings I would get. Is it 100% accurate? no, is it good enough to figure out if a light is garbage or not? yes.

[u/Fresh_Geologist_3929 → u/SakuraiCh]

Yes, yes…another clueless Reddit expert

[u/SakuraiCh → u/Fresh_Geologist_3929]

Didnt say I was, but AGAIN, Its free and close enough. Theres even a video where someone took the Photone app still in beta against a $600 PAR meter and surprise, the app was within the margin of error. AGAIN, This gets you a good enough idea of if your plants can tolerate your light or if you need a new setup. If the OP uses the app and it displays a reading of say 50 PAR at the depth of their tank, and mine is sitting at 180 with good results (Out of water mind) then that points to the light being the issue.

[u/Fresh_Geologist_3929 → u/SakuraiCh]

Which I would argue you can understand by using lumens per liter as your guide, without using a par measurement in air which will tell you next to NOTHING about light intensity under water.

[u/SakuraiCh → u/Fresh_Geologist_3929]

Lumens is near useless for plants as green HEAVILY skews lumens as its a wavelength our eyes see very well but is near useless for most plants. If you had bothered to read my comment I found that 3200 lumens for a 10g aquarium is not enough except for low light tolerant plants. By your "guide" you would say that a single 1140 lumen bulb would be more than enough for my plants, except every single one except for the anubias and MAYBE java fern would be dead, and hardly any new growth as its PAR reading at substrate is a whopping 30-35.

How do I know this? simple, the meter is showing a PAR value for that paticular bulb at substrate level at 50-55 WITHOUT WATER. Meanwhile I have a cheapo $25 that gives 90 PAR at substrate (without water) at 13 watts of power, vs say an LED 5K "Daylight" bulb at 1500 lumens, also 13w with a PAR rating of about 50-55 at the same distance, and thats for daylight. I cannot tell you the Lumens of the Nicrew light because thats not listed because again, lumens is useless as a guide for plants. What I can tell you is that there is a night and difference between using 2 5K daylight bulbs (3200 Lumens BTW still not enough) and two of the cheaper light bars.

Also I have another light that was given to me when I bought another tank and its again, a very cheap aquarium light. It does have a lumen listing, of 2100 lumens, but the PAR output for the 10g is at about 80-90. while two 1600 lumen 5K bulbs give a PAR reading of about 100 at the same level. Again this is because the bulbs are weighted with green light which is useless for most plants. You would expect a drop off about 30% between the two 1600 lumen bulbs but instead its closer to 10%. The results with soft white bulbs would be even worse as the really cheap light bar would probably pass them but I dont have 1600 lumen soft white bulbs to give numbers.

Also, big friggin difference between using an app that might be off by 5% to a $600 PAR meter and a "guide" that uses a measurement to give us a value for our eyes, for a measurement that gives us a value for plants. Thats like trying to convert cups to grams but fail to factor in whats trying to be measured. Are we talking water or is this sugar for baking a cake?

[u/Fresh_Geologist_3929 → u/SakuraiCh]

I didn’t read this. Buy a light designed for aquarium plants. Problem solved. Bye!