Thanks for the replies guys!
Actually I have 5 CO2 injected tanks. The two biggest I started up a year or so ago, and all of them have given me new experiences.
1. The 70*70*70 cm cube was originally a low tech that grew (relatively easy) plants excellent although it took time to get on top of the hair algae. Substrate is dirt plus gravel on top in this one. I converted it to a CO2 injected tank last autumn I think and everything went relatively smooth. Lately, however, plants are stunting in this tank and I have what seems to be CO2 related problems with e.g. H. pinnatifida. In this tank I have really good flow, multiple filters and a koralia on top of it all so I think it is fair to say that I have made an effort to get everything right in accordance with the conventional wisdom on this forum.
Lime green drop checker here.
Since it is a good 90cm from the lights down to the bottom I am uncertain if PAR could have been too low at the substrate level. It is a Maxspect Razor so the punch should be pretty good, but I turned intensity down signficantly a few months ago since one of the things I have learned on UKAPS is that people generally use too much light.... If I only had a PAR meter I would now for sure although it is not fun to pay that kind of money for a device you probably not use more than 5 times... Anyways, a few weeks ago I increased lights again so it will be interesting too see any changes to plant health. I am also adding a GH booster now after WC, since I think it has some extra potassium (K) in it and that problem I have with the H. Pinnatifida could be K-related (or CO2 as I said above).
2. The other big tank is some 400L, 120*60*60 or something like that. LED lights from BuildMyLed. Had huge algae problems (cyano, diatoms, some other green-looking algae) shortly after starting up but after a blackout everything went away and I'm telling you it is really a djungle now
I will try to get some photos up over the weekend... Only problem here is that the Staurogyne Repens is loosing it leaves, which seems to indicate less than perfect CO2 despite the yellow/lime green drop checker. Flow is excellent thanks to a fx6 although plants certainly are getting in the way since everytning is growing so well and I evidently have a problem with pruning too much.... That said, the drop checker is placed in the most unfavorable place -- but it is almost yellow nonetheless as stated above.
3. Small nano growing really well. Substate is dirt with some gravel on top and the plants are weeping moss, dwarf sword as carpet and Cryptocoryne Wenditii (sorry for the spelling...) Used the DSM here with good results. A month or two ago I converted this tank too to CO2 from Easy Carbo. Some GDA and a little bit BGA against the front glass but nothing aggressive and not too annoying either. But I killed the cherry shrimps with a combination of too much CO2 and/or too much EI which was unfortunate.
4. and 5. are 70L OW that I started up 1-2 months ago and they are on both sides of the nano and all are connected to the same CO2 bottle with a splitter. Cyano and diatoms shortly after startup, but after a blackout and a period of less light I am on top of the algae issues although plants have not really start growing so well. In particular, I am having the same problems as above with the H. pinnatifida and S. repens which I find very annoying. The hairgrass is growing well, however and I seem to be growing not HC exactly but it looks like HC although the leaves are twice as big. I was told when I bought it that it was a Hemianthus too but I cannot remember the name now... Substrate is dirt plus gravel plus akadama on top of it all in these tanks.
In the 3,4,5 above I have really been pushing it with respect to the gas injection, especially since I accidently killed the shrimps. 3 is fine but in 4 and 5 I am still looking for the plant takeoff. I use as much gas as the guppies can handle, a yellow drop checker, lights are on full throttle again (2'24w t5 with reflectors) but so far not the vigorous growth I'm been looking for. The pH drop at least 1 degree before lights on, and this is likely not from the 2-4 ppm level since DC is green before gas on and the surface movements are not so violent in these tanks. Good flow though, especially in one of them where I have a rated 15 times/hour turnover. In this tank I just installed an UP atomizer so it will be interesting to see how that works out.
So it is relatively early days in these tanks still, but I remember my first planted tank last year (not active anymore) where I almost could see plants growing... Beginners luck or what? Admittedly I had Oliver Knott substrate in that one but since I'm dosing EI now I thought the substrate did not matter much...
Sorry for the long post -- I hope you could follow it
P.S. With respect to the Pinnatifida issues... The plants were growing emersed before I flooded them.... Maybe it is hard to make the transformation to a submersed state and this is why some plant leaves are turning transparent/falling off? Leaves seems to be getting holes too which is why I was thinking about potassium deficiency.
Cheers, Chandler