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Geomancer 01-05-2012 12:34 PM

Lightning Levels - How to tell if low/moderate/high?
Subject says it all.

What defines a low light tank? Moderate? High?

It can't be as simple as watts/gallon, as that has so many dependencies to it (spectrum of the bulb and such). Even so, do you use 'equivalent incandescent' watts? Or are fluorescent lights the standard? With the world probably shifting towards LEDs as they become cheaper this changes things again... Then depth of the water comes into play, a deeper tank will need stronger lights to reach the bottom. I'm looking at a 120 gallon, 48Lx24Wx25H.

How do floating plants affect things? Obviously they shade everything below it, and from the profiles all of the floating plants say they are quite prolific and will completely cover the top. Do you just use a net, or your hand, and scoop up a swath to thin them out? Or are they all interconnected and need cutting?

I'm doing my advanced planning, the main fish will be angels. They like a shaded environment so I was thinking something like Duckweed. They also like amazon swords, so that's going to be the background. However, I would also like some 'carpeting' style of plants to fill out the substrate and foreground ... but they usually want higher light to have shorter leaves.

Back to lighting... the canopy that comes with the tank just has a couple regular florescent fixtures, I think two 24" T8 to make up the 48" length. That's most certainly going to be 'low light' isn't it (32W total)?

I see online with DIY canopies they are usually a wood canopy that fully covers the top of the tank, do people then completely remove the old tank cover, so the lights are directly over the water? Or do they keep the tank covered with glass/plastic and have the lights above that (so a cover over a cover)?

Byron 01-05-2012 04:33 PM

With the current variety in lighting options, even only when considering fluorescent tubes, there really is no single guide to low/moderate/high light. One has to consider the type of tubes or bulbs, their intensity, and this in relation to the tank depth and length. The "guide" of watts per gallon is still touted by many authors, but this is somewhat misleading unless you know the specifics of the tube. It used to work reasonably well when most everyone had basic T8/T12 fluorescent tubes over tanks that are within the range of say 30g to 125g. With smaller or larger tanks, and with different types of lighting, many other factors affect this and the wpg thinking is basically useless.

Rather than try to provide some sort of guideline--which would be very long and complicated as it would have to take into account the various types of lighting--I'll comment on your specific tank. And I agree, what you now have (two 24-inch T8 tubes over a 4-foot tank) is low light. Anubias, Java Fern, Java Moss and some crypts is about all that would likely manage with that light. Floating plants could be used, leaving some open spaces. I would recommend upgrading to a dual-tube T8 fixture.

When I bought my three larger tanks (two are 4-foot length and one is 5-foot) I also acquired a simple glass cover set that fits the respective tank size. These sit down on the inside lip around the frame. The ones I have slide on plastic rails so the front half can be slid back almost half way, useful to feed. I remove them completely at each weekly water change because the glass must be cleaned or the constant condensation during dark and drying during light will leave the glass marked and reduce light penetration quite significantly. The harder the water the more this occurs.

This leaves you open to any light fixture, which sits across the tank on the frame. And on all three I have a dual tube T8 fixture. On these tanks this is moderate light. The majority of common aquarium plants will manage fine. Stem plants generally need more light, being faster growing, so some will and many won't last. Pennywort thrives in my tanks. Hygrophila (whatever species) will not. Swords do well, and Vallisneria and Aponogeton. Obviously any lower light requiring plants like those mentioned earlier will also do well, provided they are not in direct light. And I have floating plants in all my tanks, nearly covering the surface. This certainly affects the fish, I have done experiments for proof.

To your question of controlling floating plants. Each week during the water change I need to remove some of the floaters in almost every tank. If I don't, by the following week the top is usually completely choked with plants and the fish cannot even get to the surface to feed. And this is not an exaggeration. I have Brazilian Pennywort floating in some tanks, Water Sprite in others, both in some, and duckweed in a couple with either or both of the former. Frogbit is present but does not do very well; I believe due to the lack of open air space. I have surface fish in all tanks that would readily be on the floor if the tank was not completely covered. My fish take priority over any plant. To thin the Pennywort, I cut some of the stems, or remove some. With Water Sprite I usually remove the largest one or two plants, pulling off some of the daughter plants, so the smaller then will grow more. This more rapid growth (younger plants versus older) uses more nutrients including ammonium from the water and contributes even more to water stability.

To your plant species for angelfish. Common swords, yes. For "carpet" I would use pygmy chain sword, this also grows like a weed in my large tanks. Sagittaria subulata grows taller but combines well with the chain sword. Floating, either Water Sprite or Brazilian Pennywort. Duckweed I would not suggest; on its own I find it not very useful in larger tanks. You need something on the surface that has substance, and the dangling roots of esp the WS will be very natural for angelfish.


Geomancer 01-05-2012 05:31 PM

Thanks, that's very helpful.

Did your local store have those canopies, or did you get them online? My local stores don't have much for lighting. Just the basic replacement's for what come with the tanks, and the canopies they have are all for the smaller tanks (only a single PetSmart in the area even has the 120g for sale in the first place, thankfully saving shipping costs).

I'd love it if a local person sold Driftwood. I saw some nice ones on Ebay but they wanted $80+ just to ship it :S

Geomancer 01-05-2012 05:40 PM

One more question, what do you think of Flourish Excel?

Claims it is an alternative to CO2 injection, and doesn't effect pH. Sounds too good to be true to be honest...

I know it isn't needed, but could help speed growth ... everything has a downside though.

Nubster 01-05-2012 06:18 PM

Excel is good stuff. Used by many people. Just be careful to not overdose as it can harm fish and inverts if you do. Otherwise it is perfectly safe. It will be pretty expensive if you plan on dosing a 120g tank though. You can get some Metracide 14. It's the same thing only stronger and cheaper. You can get a gallon for about $30 and dilute it or use less in your tank. It's the exact same thing as Excel.

Byron 01-05-2012 07:09 PM

I am not a fan of Excel, though I agree it is a carbon supplement but should not be considered a substitute for CO2 (carbon dioxide). First thing, it is a chemical substance that will melt some plant species; and if overdosed [not sure how much this takes] it can kill fish. Second, this sets up a higher level of balance.

To explain the balance: Plants will grow (photosynthesize) if light is sufficient in intensity and spectrum [the first can over-ride the second] and if all 17 nutrients are available. The nutrients must be in fairly specific proportions to each other. When this state is present, we say the light and nutrients are balanced. If any one of these is increased, it affects the balance; depending upon what is increased, and by how much, a new level of balance might have to be established. And plants can only grow when everything is available and balanced.

Specifically relating this to carbon. Those of us who use the natural method of planted tanks rely on nature for CO2, and balance other nutrients (many of which occur naturally too, but some we can add via fertilizer if needed) and light. Carbon is usually the nutrient that first becomes depleted because plants need a lot of it. There is actually quite a lot of CO2 being generated in a healthy aquarium. It naturally comes from all fish, plants and invertebrates during respiration, and this occurs continually day and night. But the largest amount of CO2 is produced during the breakdown of organics (waste) by bacteria in the substrate. Balancing the light and other nutrients with CO2 is our aim. But as soon as the CO2 is increased, then the light and other nutrients must also be increased in order to maintain a balance. If this is not done, algae takes advantage because unlike plants, algae is not fussy and can increase in any light and with minimal nutrients.


Byron 01-05-2012 07:13 PM


Originally Posted by Geomancer (Post 941510)
Thanks, that's very helpful.

Did your local store have those canopies, or did you get them online? My local stores don't have much for lighting. Just the basic replacement's for what come with the tanks, and the canopies they have are all for the smaller tanks (only a single PetSmart in the area even has the 120g for sale in the first place, thankfully saving shipping costs).

I'd love it if a local person sold Driftwood. I saw some nice ones on Ebay but they wanted $80+ just to ship it :S

The glass cover sets (these are not the same as hoods or canopies) you can buy from fish stores [maybe not all, but some] and online. The light fixtures the same. I'm sure I've seen the glass covers in Petsmart here, and some light fixtures too. May vary from store to store.

The Petsmart here also has Malaysian Driftwood, my favourite (and only) aquarium wood. I prefer getting it from a store rather than online because you can see what you're getting, and as every piece is natural, each is different.

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