[Bigboy]

My question if regular light fixture came with
Aquarium is enough for low light tech tank.
And EI dozing amount I need to use if I planing to change water every 2 weeks. Thanks

 

[dubvstudent]

That depends on a couple of things. First off, what are the dimensions of a tank?

A 75 gallon is about 21" tall. There are also 80 extra highs that run around 30" in height. The depth will impact the amount of light needed. Typically the standard t8 strip light that come with kit tanks are inadequate, but there are exceptions to every rule.

As far as putting yourself in the low-med light range use the chart found here:
http://www.plantedtank.net/forums/lighting/105774-par-vs-distance-t5-t12-pc.html
It is a good starting point but don't forget to adjust for the height off the tank of the fixture.

Many low tech tanks use ferts but since the growth rate is much slower, they are used less frequently and usually in smaller doses. Along with that, water changes are needed less frequently.

See the low tech forum:
http://www.plantedtank.net/forums/low-tech-forum/
There are many useful threads here to help you get a better handle on some of the ins and outs of lower tech setups.

 

[Bigboy]

I have 80 gallon bowfront 30 inch height

 

[Bigboy]

Do you think I need to go with 2x54 watt T5 or I need to go with 4x54 T5.I guess if I go with 4 x 54 watt I need to add co2. Thanks

 

[newplanter]

I have a 90 gallon with 2x54w T5 HO GLO fixture on top of the tank above the glass cover and supliment that light with canopy DIY fixtures 2x65watt 10k's HO's without CO2. I dose Excell every other day with some trace and flourish 2 x's a week and water changes 1xmonth..tank is a year old and the plants are doing great. Very little algae now that I remedied most of the problems.

 

[NJAquaBarren]

2x54 is already plenty of light. Medium to low in the high range depending on how you mount and quality of the reflectors.

4x54 is high. You will have high growth rates either way, CO2 beneficial to both, probably necessary with 4x.

What are your objectives? We can better help if we know what you want to do with the tank.