no red light = no red coloration?

[justDIY]

my new 30 gallon planted is coming up on being 2 months old, and I've noticed several changes.

For the 1st month, nothing much grew but everything looked good

now everything is growing very quickly, but some things I'm not happy about.

firstly, here's the specs

30 g (36x12x16)
250 watt MH pendant suspended 20" above the middle of the tank, 6500k iwaski super-daylight bulb ~2 mo old
high-pressure CO2, PH 6.8, KH 4
2 HOB filters, just for water movement and some mechanical filtration (no carbon)
water temp is around 78

problems

other than java moss everywhere like a bad algae i've noticed a distinct loss of red coloration from plants that should be red.

red ludwiga for example has taken on pale red / dark green color, not the bright red I get from the same plant in another tank which has 2 6750k custom sealife PC's

sunset hygro is loosing it's pink/red coloration and turning white / light green

red swords look dark maroon, red apons look dull as well.

the ludwiga and hygro were both "normal" looking when placed in the tank, but have since undergone this color change. the red swords were always the maroon color, and I think they are still "pouting" about being moved, as they're not growing much the red apons I have no refrence on, as they're growing from dry bulbs.

I suspect the cause of all of this is the lack of Red and/or Yellow light from the light source? All the greens plants look great, and the tank seems to have an overall bluish-white appearence to it. I'm trying to think now how I can add some red light, without having to put a fluorescent hood/canopy on the tank

any thoughts and suggestions are appericated
Gordon

 

[Allivymar]

Just a coupla thoughts, as I am quite the newbie on planted tanks:

One of the things I know red plants need is lots of light. It SOUNDS like you have more then enough, but maybe 20" is too high for the MH? I don't know what sort of spectrum the MH offer, but yeah, if its mostly blue/green I can see where it can be a prob.

Also I've read red plants need iron fertilization. Any idea what the iron levels are?

I realise I'm not much help LOL but its a place to start

*edit*
Ooo, came across this website; maybe it'll help? http://www.fishnphoto.nl/actviv/aru/ARU2E.htm
Its sorta written in engrish LOL but it IS readable; follow the links for specifics on the diff plants

 

[justDIY]

well, I am using schultz profile for a substrate, and the tap water here is rather rich in iron (may only be oxides however)

I did put some iron tabs in the gravel recently, will wait to see if that helps anything.

thanks for the input thus far!

gordon

 

[tkos]

Generally it is lack of iron that makes red plants loose their reddish colour. Hopefuuly the tabs will help. An iron rich fertilizer added weekly will help.

 

[justDIY]

well I've thought some more about the iron

ludwiga growing in my established 29 gallon tank (18+ months old) grow very bright red. that tank has a sand / aq gravel substrate, minimal diy'd co2 and 6.6 wpg (two 6700k custom sealife bulbs).

the only place that tank would have gotten iron is from accumulated fish mulm... chelating in the gravel from anaerobic bacteria colonies...

however, even ludwiga growing in a small pot of profile in the 29 gallon is decently red.

-----

if i go to the city this weekend, I'll get some more ferts.

 

[Doraemon]

I don't believe that the red lights will help the red plants. We see these plants as red because they are absorbing all other colors of the spectrum and reflecting red. I agree with Allivymar. I'd check the iron levels.

 

[Guest]

Fom what I've heard, most iron tests are pretty unreliable. Also, the fact that your plants with virtually the same conditions, except for the lighting, are nice and red in another tank leads me to believe that you were right in the first place. I'm thinking its the lighting, there must be something missing in the spectrum. I have no idea how to correct this.

 

[justDIY]

well ... I've been running a pair of 100 watt halogen spots above the tank for a few days now, and have already noticed a small difference!

the swords and crypts which grow red leaves are now much more red looking, and some apon's also have more red.

I'll need to look into alternatives for these halogen though, they put out a lot more heat than light!