Lighting

[Fly258]

I have a 70UK gal heavily planted community tank with 2x40 watt tubes, 1x powerglo and 1x aquaglo. Reading through the posts on lighting, the recommended minimum power seems to be 3 watts per gallon. If that IS the case, then I should have 210 watts ie 5x40 watt tubes! This seems a little excessive as the tank seems very bright already and I dont think I could fit them all under the hood.
Most of my plants seem to be suffering, turning brown or yellow although a few are still bright green and healthy looking. Would increasing the wattage re-vitalise my plants or do they need something else, CO2, food etc?
Many thanks
Jim

 

[njparton]

It does seem a lot.

However it also depends on the type of plants and the depth of your tank.

I have a 140L tank with 3 x 25 W tubes which do very nicely.

I heard 2W/gal minimum (not that it makes all that much difference).

When I was having problems growing my plants I added some liquid feed to the water and some of the quicker growing plants in my setup literally went through the roof!

I invested in some root tabs a few weeks ago and put them in the gravel round the slower growing plants and they're doing well now - one even looks about to flower!

 

[George Farmer]

I use two 18W lamps in my 125 litre (33 US gallon/27 UK gallon) which equates to less than 1W per gallon. However I use reflectors which double the output and I'm not sure if this is taken into account. I do know that my plants thrive, you can see my setup http/fish.orbust.net/forums/index.php?sh...showtopic=15694

I believe you need a few things for good plant growth, quality lighting, a nutrient rich substrate/substrate heating, decent liquid fertiliser and most important good water quality, most plants like pH 6.5 to 7.5, KH 2 to 6 degrees. Regular water changes ensure they're getting plenty of nutrients. CO2 will benefit of you have enough light.

 

[njparton]

I use two 18W lamps in my 125 litre (33 US gallon/27 UK gallon) which equates to less than 1W per gallon. However I use reflectors which double the output and I'm not sure if this is taken into account. I do know that my plants thrive, you can see my setup http/fish.orbust.net/forums/index.php?sh...showtopic=15694

I believe you need a few things for good plant growth, quality lighting, a nutrient rich substrate/substrate heating, decent liquid fertiliser and most important good water quality, most plants like pH 6.5 to 7.5, KH 2 to 6 degrees. Regular water changes ensure they're getting plenty of nutrients. CO2 will benefit of you have enough light.

Good point about the reflectors - I have those too.

I'd disagree about the liquid fertiliser though - it's not selective enough (all or nothing). With root tabs you can choose which plant to fertilize.

 

[George Farmer]

Fair comment about the liquid feed. I guess I'm just lazy (and tight)!!

 

[Fly258]

I read that aquarium plants take most of their nutrient through their leaves not their roots. The roots are used mainly for anchoring.
Jim

 

[Rose]

Yellowing leaves tend to mean that there's not enough iron in the water for the plants. Try that and see what happens. Seachem makes a liquid iron that is very good. I use it and have had great results with it.

Rose

 

[njparton]

Yellowing leaves tend to mean that there's not enough iron in the water for the plants.  Try that and see what happens.  Seachem makes a liquid iron that is very good.  I use it and have had great results with it.

Rose

Some of my plants do suffer from yellowing leaves - I'll give the iron addative a try

I just hope it doesn't also contain a plot of phosphate. I've used some Seachem pH adjuster in the past and it was full of free phosphates caused an algea bloom that took 4 weeks to get rid of

 

[Ob1]

I disagree

I use reflectors which double the output

I understand that low power tubes sub 50watts cannot obtain a 50% improvement in power by using reflectors the is in fact improvement only something like 2-5%

I was going to purchase reflector for my 4X46inchT8 tubes each one 36watts and the shop suggested I stay with the flat white background it is just as good at these power levels. Reflector only improve high out tubes…

 

[jhd]

Guys, let’s clarify reflector issue.
Reflectors do not double the output. If they did, you could direct reflector into the scope of another reflector and another one and if you have enough reflectors, you could have nuclear reaction energy from the single candle light.
Light bulb emits light energy evenly all around. If you have reflector, you just RECOVER half of the energy that would otherwise go upwards from the water surface.
If you have white paint or plastic you can only recover 70-80% of that half.
For mirror reflectors, it is 90-95%.
So with white paint high gloss for 40 Watts you can have 34-36 Watts effective,
BUT:
For fluorescent light, ballast rated 40 Watts never actually delivers 40 Watts.
Only VERY good quality ballasts deliver close to 40 Watts, you can count on 35 most likely.
So realistically you have just over 30 Watts directed into the water.
Hope it helps.

 

[EddieW]

NJP,

I just hope it doesn't also contain a lot of phosphate

I rate JBL Ferropol - I think it is a good fertilizer and contains no nitrate or phosphate.

Eddie

 

[njparton]

NJP,

I just hope it doesn't also contain a lot of phosphate

I rate JBL Ferropol - I think it is a good fertilizer and contains no nitrate or phosphate.

Eddie

Thanks, it turns out Seachem Flourish contains no free nitrate or phosphate either...