No pearling?

[nanogal]

Hi guys, I have 2 wpg with a little diy yeast co2 injection, and my plants are doing fantastic, but I only ever see pearling when I do a water change.  After a few hours, it just looks like a green forest again.  I could replace the bulb the tank came with, but max output is 15 watts,so 3 wpg, but I am wondering if my water is just low in oxygen and therefore does not saturate, or if I need a better means of dissolving the co2.  I need to get some more test kits, because I enthusiastically used them all up while I was cycling the tank ,
I suppose at first I was just thrilled to see growth and not the morbid plant death I had experienced with previous attemps, but now I want MORE!!!  I want that pretty pearling  
My plants do grow like mad and I prune weekly, but I guess that's not saying much because in 5 gals, if I don't prune often, it turns into a jungle.
Do folks sell test kits at the giant auction or is a trip to the store in order?

[Toss]

More CO2 will help

[fischkopp]

... and more light

It also depends what kind of plants you grow, some pearl more than others given the conditions are right (a LOT of light+CO2+other nutrients)

The pearling you notice after a water change comes from dissolved gases in your tap water, not from your plants. They gas out as soon as the temperature rises and the pressure lowers.

[charlie]

i agree that the bubbles after water change is not pearling, also take note that the WPG rule of thumb does not apply to small tank below 20 gallons & large tanks above 75 gallons, in a nutshell , a small tank like yours will reguire a lot more light to get it to a meduim light tank.

I would suggest that if your tank is doing good as is & you are getting good growth & the algae is at bay , take that as a sign that the tank is balance , don`t try to change anything to acheive pearling .
Just my thoughts.

[nanogal]

Ok, good to know about the whole wpg rule not applying to small tanks, but I do have some bba...
I had a good deal of thread algae for about three days and it disappeared, probably thanks to my lil oto, but the bba is still there, not out of control, but definitely present.  Will my little cherry shrimp help with that?  Or should I invest in some excel?
I have hygro polysperma, what I think is an A. Crispus (they always have them at BA Innes) a sword plant of unknown identity and java fern and moss.  I don't know that these are really the right plants for such a small tank, but I asked for stuff that I wouldn't be able to kill if I tried, and so far they are doing great, but I think I may eventually want to trade em' in for smaller plants that I won't have to prune constantly and will look better in my size tank. 
I guess I can live with no pearling, and I suppose my plants are not exactly poster children for pearling either...

[charlie]

Ok, good to know about the whole wpg rule not applying to small tanks, but I do have some bba...
I had a good deal of thread algae for about three days and it disappeared, probably thanks to my lil oto, but the bba is still there, not out of control, but definitely present.  Will my little cherry shrimp help with that?  Or should I invest in some excel?
I have hygro polysperma, what I think is an A. Crispus (they always have them at BA Innes) a sword plant of unknown identity and java fern and moss.  I don't know that these are really the right plants for such a small tank, but I asked for stuff that I wouldn't be able to kill if I tried, and so far they are doing great, but I think I may eventually want to trade em' in for smaller plants that I won't have to prune constantly and will look better in my size tank. 
I guess I can live with no pearling, and I suppose my plants are not exactly poster children for pearling either...

Excel would be economical for a 5 gln, will defiantly help with the BBA.

[pitabread]

I think you'd need a lot more light and CO2 to get pearling in a 5 gallon.  FWIW, I have a 5.5 gallon with 27 watts of light and DIY CO2 and I don't see much pearling.  Although admittedly I don't think much CO2 stays in the water, so I dose Excel as well.

[nanogal]

Ok, thanks a lot guys, but my bf and I are doing tons of research about lighting and compact fluorescents in particular, for the 10 gal we just got at the auction.  Could you pls give us a little advice?  We have replaced the incandescents with two 10 watt daylight cfs at 6500 K, CRI 79.  Is that enough to grow some decent plants?  They're from Canadian Tire, GE brand.  I don't expect pearling, just decent growth.

[fischkopp]

I would consider two 10W over a 10g as low light. I have the same setup and keep basically undemanding plants like crypt, swords, fern, anabia and javamoss in there. Another 10g has two 23W, which is more medium light and requires CO2 to keep the plants happy. This setup can grow more demanding plants like reddish stem plant

[pitabread]

I made a lighting chart which scales the old WPG rule to tanks of different sizes based on surface area, not volume.  You can use that as a rough guide as to what lighting to shoot for.  Also, those 10 watt compacts: are they spiral compact flourescents?  Because spiral compacts tend to be not overly efficient light sources due to the spiral design (lots of restrike).  Straight tube compact flourescents would be a much better choice. 

[nanogal]

yep, spirals. 
Thanks guys, I'm always looking for more info so you're all being really helpful, but I am not quite ready to invest in high light I think... 
I know where to ask when I am though

Here are a few residual questions, however:
1. Does the colour temperature really matter?
2. How much less efficient is the spiral design, not sure where I can get straight CFs that will fit in the canopy.
3. The CRI has nothing to do with growing efficiency does it?
4. When considering WPG with CFs, does one consider the incandescent equivalence, or its straight wattage? My lights are 10 watt CFs, with a 40 watt incandescent equivalence...

[pitabread]

1) Not so much colour temp as spectral output.  Plants primarily absorb light in the red/blue spectrums, so you want bulbs that output light in those spectrums.  Generally, 6500-10000k bulbs usually do that.

2) Not sure how less effecient they are, but to use straight tube compacts you'll need to replace the light fixture as they require a seperate ballast and different connectors.

3) ?

4) Straight wattage.  Incandescent wattages are misleading, since incandescents release most of their power is released as heat, not light.  That's why compact fluorescents can release the same light with so much less power use.

[kennyman]

I like your spread sheet Pitabread. It seems more in line with practical application of lower light tanks than most of the stuff I have seen.

[fischkopp]

I made a lighting chart which scales the old WPG rule to tanks of different sizes based on surface area, not volume. 

Neglecting the volume of a tank and only using the footprint doesnt take into account that the hight of a tank is different. In fact, if you compare a 20H with a 20L than the high tank will require more WPG than the long tank to achieve the same results. The table seems to tell the opposite. Maybe I dont get it right, the cell values represent watts, right?

[pitabread]

Neglecting the volume of a tank and only using the footprint doesnt take into account that the hight of a tank is different. In fact, if you compare a 20H with a 20L than the high tank will require more WPG than the long tank to achieve the same results. The table seems to tell the opposite. Maybe I dont get it right, the cell values represent watts, right?

Yes, the cell values represent watts.  I didn't take into account height, except that I limited the tank sizes to tanks that are 24" or less.  From my research, tank height doesn't appear to affect light levels all that much, except from point light sources (i.e. metal halides).  However, if someone can give me data on the scaling of light levels versus height, then I can add that dimension to the chart.

[kennyman]

Peter Hiscock in his book "Complete Encyclopedia of Aquarium Plants" feels that depths over 15" begin to significantly impact how much light reaches the base substrate. Also I believe that point source light penetrates far better than the diffused light of tubes. I am not sure which way you were meaning that.

[pitabread]

What I recall reading was that the light drop of for point light sources was exponential, while the drop off for linear sources was linear.  The flip side is that they make up for it via sheer intensity.  At least that is what I remember.  I could be wrong.

I'd like to know more about height and light drop off, because it would be nice to add that to the chart.  Does the book go into any mathematical detail?

[kennyman]

His book does not. I do have some books that list light penetration but they are natural sunlight in meters of water.

Someone did a study by measuring intensity from different light sources in filled aquariums on one of the online SW sites. I think Our Social Convener, Redbelly(Patric) at Ottawa Inverts was pretty interested in it awhile ago and If you send him a pm he might be able direct you the correct forums where it was posted.


But how much does the lux come into play with respect to these small tanks? Do you not need to cross a certain minimal lux level to initiate plant growth?