How Many Watts For My Tank Please?

[jagillham]

Hi all,

Can anybody advise if my lighting is sufficient for my tank?

The tank is about 400l, approx 120cm x 60cm x 60cm (4'x2'x2' in old money!).

I am dosing EI daily and inject CO2 via a FE. I want to increase the plants towards a jungle look, so lots more to go in

Currently I have 2x T5 39W lights with reflectors running 3pm to 11pm daily.

Thanks in advance!

 

[ian_m]

Using the graph below with 24" depth gives about 45 par per tube -> 90 PAR total so bottom of high light area. So yes lighting is adequate for a high tech tank.

So patience and allow the plants to grow is the solution.

 

[jagillham]

That is surprising, I worked out the wpg to be 0.7 which comes in at 'low' if I am understanding correctly.

 

[jagillham]

Oh, and I have my lights above the glass sliders. Does this make any real difference?

 

[ian_m]

Oh, and I have my lights above the glass sliders. Does this make any real difference?

Yes...not too sure but remember seeing 30-40% loss especially if covered in moisture.

How were you intending to add more light anyway ?

 

[jagillham]

That's potentially a lot, especially where I'm hard water so have the limescale deposit too to contend with. I'd just add another light set. Mine only sit loose on the glass at the moment.

 

[EnderUK]

Wattage per gallon is a dated method of light measurement when people hadn't the access to par meters. 50 µE m−2s−1 at substrate level should be more then enough to grow most plants.​

 

[Crossocheilus]

Ian, is the distance on the graph distance through water or total distance including air (like with hanging light)? If it is just water (judging by your response to the original post) then do you know how to work out par through air and water?

 

[EnderUK]

There's generally no difference in par levels measurements through water and through air. There is some refraction and reflection as it passes through the different mediums but again this is generally minimal. If you go over to the planted tank forums you can see the whole in depth theory behind the graphs. Just Google par vs distance and it should come up.

 

[Aqua Hero]

yeah i didnt so research and learnt about the par vs distance. most of my plants are said to now grow if i dont have min 1.5 watts per gallon. i have 2 24w t5ho bulbs and my tank is 60cm deep but all my plants are pearling and i have to constantly trim my plants every week. heck i was even able to resurrect some close to dead java fern with the help of excel

 

[jagillham]

Thanks for explaining that! Time for some more plants

 

[ian_m]

min 1.5 watts per gallon.

Remember the Watts per gallon research was all done on US gallons which are not same as the bigger imperial gallons.

1 UK gallon = 1.2 US gallons.
1 UK gallon = 4.54 litres.
1 US gallon = 3.79 litres.

So using UK gallons you will be underestimating the light.

 

[jagillham]

Dragging up my own old post here...

Here is the tank around 5 months down the line. Still dosing the EI daily and the drop checker is always green. Not really too happy with thinks as they stand. The Blyxa Japonica still does not grow as bushy as others seem to get it. I'm replanting the runners as they appear, but each plant is a bit spindly still.

The Staurogyne Repens has all but died off too. Most of the plants seem to have been making a dash for the surface rather than filling out. I come back to the idea maybe the light is not enough. I have glass sliders, and also the tank is almost 2ft / 60 deep.

Any recommendations on what to do?

 

[Andy D]

How is the tank filtered?

Elongated plants are usually looking for CO2 and not light so this may be a sign that the CO2 level at the substrate is poor.

Can you put the drop checker lower and see how this measures?

 

[jagillham]

Filtration via sump. Think the return pump is the Eheim Compact 3000+. The exit is out the side of the weirbox pointing towards the powerhead. I feel like I have the flow sorted, every plant in there is swaying slightly.