Time to change tubes?

[scottward]

I have 120 watts of T8 light over my 6' tank for 12 months

Things have generally been ticking along ok (still experimenting with CO2 though).

E. Tenellus right at the bottom of the tank is still growing ok, putting out new runners etc, so I'm inclined not to worry about changing the tubes, even though it has been just over a year that I have been using them.

I notice that my Ambulia is looking a bit 'leggy'. Can this legginess be just due to the fact that this plant is greedy regarding CO2, and I'm possibly not feeding it enough CO2, or could I use this as an indicator that the tubes could do with replacing? I haven't always had it in the tank, so I can't conclude that it (the Ambulia) is doing worse as the tubes get older.

What's a good 'canary' (good term used by Tom) plant to check lighting levels?

Maybe I can just keep running the tubes till they drop?

Scott.

 

[shoggoth43]

I wouldn't wait until the tubes drop as such. You'll then end up replacing the tubes with much brighter tubes, which will end up suddenly increasing the demand for ferts and CO2. At that point you're more likely to get an algae outbreak. I think there's a thread on here showing 18 - 24 months is fine for a swapout but I can't recall it at the moment.

-
S

 

[scottward]

Yeah, that's a good point about the sudden change.

Is there any thing I could look for in the tank, perhaps a particular type of algae, 'canary' plant, or something like that, that is a good clue that the light is starting to become too weak? Or does that thread basically say that it's based on time?

As I mentioned earlier, the E Tenellus is still growing and it's right at the bottom of the tank, I suppose it would stop growing if the light got too weak.

 

[nipat]

I wouldn't use Tenellus as a canary for lighting. My 20 gallon tank
used to have 2x18w T8 with about 70% of the bulbs covered with paper.

Blyxa started to leave the substrate, Vallisneria became smaller
and smaller, Heteranthera Zosterifolia melted. Even algae like
Spiprogyra was gone. Only two kinds of plant were fine: Tenellus
and Vivipara.

Oh, and Oedogonium. This alage could grow even on lowest
Tenellus leaves under this light level. I think the reason I can't get rid of it
is overcrowding.

 

[scottward]

Ok, cool. Thanks for the info about the Tenellus. It's interesting to note that this same plant also does ok when other plants are starting to show CO2 deficiencies. The tenellus will pale of a bit though, but it is probably the best plant in my tank, as it grows well and is nice and tough (and looks good too).

Could the legginess of the Ambulia be telling me that I need to change my lights - or could this purely be CO2 related?

 

[scottward]

I actually have 8 x 30w T8 tubes over my tank, 4 rows of 2 (it's a 6 foot long tank).

So I have been running only 2 rows for about 12 months, from the front of the tank I have had the first row on and the third row on. Yesterday I decided to turn on the fourth row (i.e. the row closest to the back wall of the tank), which adds an extra 60watts of lighting.

The stem plants, particularly the ambulia, are looking a bit leggy and growth is very slow. I'm thinking that perhaps I need to ramp things up with just a touch more light.

I have an AM1000 running + a needle wheel. The tank is absolutely full of CO2 mist and I have a koralia swirlilng it around.

I'm hoping that with the increase in light I can make those stem plants start filling in faster. I am dosing full E.I. So all I really have to do is keep an eye on the plants and after a week or so if they don't appear to be growing I should just progressively crank up the CO2 even further?? I'm not sure whether to turn up the AM1000's bubble rate, the needlewheels rate, or both?!??

Thoughts?

Scott.