[aclaar877]

This sounds crazy, but I ran a 155-gallon aquarium with DIY CO2 for five years with pretty good results. I grew swords, vals, crypts, cabomba, ludwigia stem plants like crazy and would routinely sell $30-$50 of clippings at a time. Lighting was 4x96W PC, single T8 and dual T5 NO, with fluorite substrate. I had trouble growing A. Reineckii and Rotala Wallichii and Ammania Gracillis would have a red top but lose lower leaves, but otherwise the tank did great, even at 84 degrees for discus.

This year, I invested in pressurized CO2 and the BML Dutch XB LED to replace the PC fixtures. LED is raised 3" off top of tank, and I run it about 80% strength. The pH drop is 1.4 using the de-gas method, and I've tested that 2-3 different times, always getting about 1.2-1.4 difference. I run CO2 through two PVC reactors on canister filter returns. Pearling is great, and plants look good under the light, but growth rate isn't that much different (swords and narrow leaf ludwigia are actually slower and crypts aren't getting as big as they used to). Alternanthera Reineckii still looks terrible-I get maybe an inch of growth in 2-3 months, and lower leaves are yellowing, ratty, and have a little spot algae on them. I got Ludwigia Glandulosa a month ago, and it's transitioned to submerged growth with a nice red top, but it has lost a lot of the lower leaves. CO2 mist is directed onto both of these plants.

Ferts - with DIY CO2 and PC lights, I probably did about 1/2 EI, and based on API test kits maintained NO3 about 20ppm, PO4 at 1-2ppm, and added K and traces to the point I never saw holes in leaves, stunted tips or pale leaves. With new lighting and CO2, I have tried full EI, half EI (since tank is moderately planted) and modified EI (holding back on KNO3 since test kit shows 40+ppm and just dosing K2SO4, 20ppm per week). I maintain 50% weekly water changes. At 5-6 days after water change, tank looks generally worse than it does 2 days after W/C, with more GDA, some fuzz algae on hardscape, etc. I usually notice this right after full CSM+B dosing. Algae situation has improved recently as I have cleaned filters more often and removed mulm and dead leaves more often.

I read with interest some posts by Kekon and Defdac, suggesting that high NO3 combined with soft, low-KH water could drive plants too fast, notably A Reineckii and result in stunting similar to calcium deficiency. My GH is 7 and KH is 4 (I raise it from tap, where it is at 2). I could never get nitrate down that low (5-10), and in trying to do so I noticed ludwigia lower leaves looking bad and the plants not growing much. Plus Tom Barr grows these plants in high nitrate and soft water, so I determined it was easier to raise my KH rather than trying to walk a tight line on NO3. No improvement on A Reineckii. I have also tried Jobes sticks under them, and I have placed stems under each type of light in different parts of the tank. None of that makes any difference. That some people grow AR like weeds blows me away-I can't figure out how they do it.

My goal is to keep L. Glandulosa alive, keep most lower leaves, and get A. Reineckii to grow. I don't even care if it grows green - just grow! I'll worry about turning it red later... Top leaves are red, so I assume its getting enough light and iron.

Options:

Should dim the LED further? I estimate right now that halfway down the tank I have over 100 PAR directly under the fixture, based on BML website. At substrate I should have around 50. That should be enough to keep lower leaves of stem plants, right? Can AR grow at substrate at PAR of 30? (Plants are 1-2" tall) I wonder if the light is causing other plants to out-compete AR for CO2 and/or nutrients.

Could I still be short on CO2, even with a 1.4 pH drop? Even with some margin of error on test kit I should still be at least 30 ppm. I don't see any fish distress at level I have, and I could probably turn it up more. I don't think its a distribution issue, with two reactors, lots of mist and noticeable flow around all plants.

Could substrate need replacing? I have 8 year-old fluorite, 4" deep.

Is there anything off in fertilization? I have two API nitrate kits - one at least eight years old and one bought this year. Readings are beet red on both of them. Should I try to get NO3 down to 10-20 ppm, or does it not matter if I have way over 40 ppm? Does the fact that the tank looks worse 5-6 days after W/C suggest I'm dosing too low on anything? I get GDA on glass, but not a single spot of GSA. Thankfully I have no BBA or hair algae either. If ferts were the problem, two weeks of full EI should have shown improvement. I get Leibig's law, but it seems like I have a lot of everything yet the plants aren't responding like they should.

I can add some photos later, but the AR looks similar to many other photos posted by people having trouble with it - lower leaves rotting away with some algae on them. Solution is usually more CO2, but I have tried that to no avail.

 

[Xiaozhuang]

btw are you talking about normal AR or AR mini?

 

[aclaar877]

Normal AR - They just don't seem to grow at all.

 

[BruceF]

I would think that the loss of lower leaves was either due to transitions or to lack of light.

 

[Xiaozhuang]

Hmm may have to see your photos to make sense. The default/common AR grows faster than the other AR varietals. I find that the AR cardinalis I was sold grows more bushy under high light; there is alot of side shoot growth even though vertical growth is slow. The AR mini I have grows quite fast, though it tops out at a maximum height faster than the AR cardinalis. The AR "Rosanervig" I have also grows slowly, like 2 inches a month. Overall they don't seem to like being moved around, though they take to pruning quite well. Maybe you are growing a particular varietal instead ?

 

[aclaar877]

Yeah, I very well may have one of these. I do have Cardinalis from Petsmart, so that may explain the lack of vertical growth. No idea what the other kind was that I bought a year ago - it was about six inches tall and in rather poor shape from a LFS. I may try to trade locally for the Lilacina variety, which I believe is the easiest to grow. I'll try to get photos posted tomorrow.

And on Ludwigia Glandulosa question, I saw some of Tom Barr's old photos where he grew it under T5, and it looked great with plenty of lower leaves. So, putting it directly under LED ought to be enough light, if anyone else has that same question.

 

[Xiaozhuang]

I bought a BML series also, and will run it on this current tank with has all 3 kinds of AR and L. Glandulosa as well (currently running on budget old school Metal Halides). Can do a growth comparison then, never had much of an issue with Glandulosa though, except that it takes up quite abit of space as they grow big

 

[roadmaster]

I am no CO2 Wizard but I might wonder if Reducing the intensity of the light to say 60% or 70 % might not be wise considering it will reduce demand from plants for CO2 and fertz .At least this will give you some time to ensure good CO2 distribution and resume full EI dosing.(nothing good comes from limitation)
I might wonder if CO2 is on timer to come on at least one hour before lights come on for the day? It was not clear if pH drop is right at lights on or at some other point during the photoperiod.
I might place spray bar(s) from filters on back glass about an inch below the water line to force the water down against the front glass,across the substrate front to back,back up the back glass.This might help lower leaves catch more of the gas.
Some folks place diffuser under the intake for filters and this helps chop up the gas and helps with distribution as it leaves the spray bar or return.
Some also report that canisters sometimes cavitate, or burping sound comes from running the gas through the intake of the filters but that if some of the media is removed,this can solve the cavitation while also increasing flow/distribution which is a good thing.
Might also consider if sump is being used,,that a lot of the gas is being quickly lost and maybe there is not the CO2 that one thinks there is being circulated throughout the tank.
Don't know how long the more demanding plants have been in the tank but I might try all or some of that I suggested and give the plants some more time.
Folks often believe that when they inject the gas that they also need to increase the light but those who do indeed appear to me to be Wizards with CO2 tell me this is not true at all.
Me thinks in truth,,you can run however much light you want over low tech,or high tech,but you better be able to raise the light up away from the tank till you find the sweet spot with both methods.
My two cents,

 

[aclaar877]

Roadmaster, I've been considering lots of things you mentioned. I think I still have headroom for some more CO2, as no fish ever appear to be stressed at any time. The pH drop is comparing pH at end of photoperiod (6.1) with a water sample de-gassed and checked a couple days later (7.5). I have been thinking of doing the horizontal spray bar as you mentioned - I looked for some Rena spraybar extensions and can't find them. So right now I only have two bars about 12" long, which on a 6-foot tank may leave too much dead space in that configuration. Lots of the CO2 mist from reactors comes out the bottom elbow, so mist is hitting the lower leaves pretty well right now. I'm using two canisters, no sump, so I don't have much CO2 loss. I am also learning not to trust test kits and be more disciplined in fertilizing, and I agree that turning the light down some should help the CO2 competition.

Everything except the A Reineckii seems headed in the right direction - I'm getting great growth on narrowleaf ludwigia and L Repens, vals are sending runners, swords are getting bigger. I may scrap the AR and find some Ludwigia SP, and use that and Glandulosa as my red plants...