Ensuring a Healthy Low Light Aquarium

[Satsumas]

I have a 20 gallon tank which still has its standard 20W flourescent bulb and i have various crypts in there with java fern and an anubias.
However i am going to perform a substrate change and get rid of all the plants in there as they are covered in algae and are unhealthy do to an overfeed when i was on holiday.

I have some new plants in mind but what could i do to ensure that they stay healthy?
I was thinking about mixing substrates together as i would like white sand but also a good nutreint base for the plants and maybe an undergravel heater aswell?
I dont want to add CO2 but would ferts be a good idea? or maybe some trace elements a few times a week?

 

[theotheragentm]

Light is the first thing that is needed. Then it's carbon, your macro nutrients, then micros. If you don't have lighting in place, there shouldn't be a need for ferts.

 

[black hills tj]

From what I've seen...most plants can adapt to any lighting situation. Here's the deal though. With lower light(your tank for example, 1 watt per gallon) the plants don't take up the nutrients as fast and grow slower. Therefore, no need for CO2 or ferts. Now with higher light, we'll say for example my 29g tank which has 65 CF watts over it, the plants suck up the nutrients quicker which means I need to dose ferts to replenish the nutrients in the water. This way the plants have adequate nutrients and grow quicker.

 

[7Enigma]

Low-light tanks rarely need to be treated any differently than fish only tanks. As long as the flow is kept up (to prevent stagnant areas) the needs of the plants should be more than taken care of by the feedings.

Mixing substrates is normally not advised since it will look mottled very quickly (denser/larger particles will sink to the bottom). Also in low light environments the plants will be just fine with water column feeding (you shouldn't have any swords or other heavy root feeders in a low-light tank IMO).

I've never used an undergravel heater, and have no problems growing plants fine at both low and high lighting. I'd be concerned about anaerobic issues with localized elevated temp areas (near the heater) where you will speed up the metabolism and thus generation of toxic gases such as hydrogen sulfide. Again in a low-light tank, its just not needed.

Keep up on the water changes, get a good algae eating crew if you can house them with your types of fish (I recommend Oto's, BN pleco, MTS, true SAE, nerite snails, etc.), and you should be fine.

 

[Jchillin]

Here is a recent reference thread on this topic.

A low-light tank can produce algae just as easy as a high-light tank. I've been experimenting with this for the past two years and found that having some nutrients/ferts on hand can do wonders, especially if your "low-light" tank is seriously populated with a ton of plants.

FWIW, I'd ditch the UG as it is not going to provide any appreciable benefits and will more than likely create problems as 7 pointed out. I've seen successful tanks that use Pool filter sand only however, I second the suggestion of ramshorns and especially MTS which will do everything in their power to eliminate any anaerobic pockets.