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Discussion Starter · #1 ·
My tank is a 20g low light fully cycled

Here are the parameters :

Lightning = Current USA Freshwater Led+ (currently on 8 hours photoperiod 2PM-10PM)
Substrates = Seachem Flourite
PH = 6.8
GH = 40ppm
KH = 30ppm
Ammo = 0
Nitrite = 0
Nitrate = 2.5ppm

Fauna = 9 x cherry barbs (3 x males, 6 x females) and 3 x amano shrimps
Flora = Java fern, Java Moss, Anubias, Vals, Sword, dwarf sag

Fertilizer = weekly recommended Flourish comprehensive dosing + DIY osmocote plus root tabs

I am planning on dosing daily metricide which just came in today. I will start at 0.6x recommended Excel daily use since I wont dilute it. My concern is I am working from 8AM to 5PM. From what I read it is recommended to add Excel BEFORE lights on. That leaves me with 3 options :

1 - leave the light schedule as is (2PM-10PM) and add Excel before going to work at 7AM (lights would come up 7 hours after adding excel which seems to be counter effective)
2 - Leave the light schedule as is (2PM-10PM) and add Excel when coming back from work at 5PM (lights would be up for 3 hours already when Excel is added)
3 - Do a split photoperiod (8AM-noon and 4PM-8PM. During the rest period the tank will receive a slight amount of indirect light) and add Excel before going to work at 7AM

I tend to go toward #3 but I am open to your toughts/recommendations.

Also, should I dose Macro nutrients or will the Flourish comprehensive suffice (everything is doing fine aside from a very small amount of BBA on my java ferns which I hope metricide will get rid of and my anubias leaves shows some holes which I believe could be a Potassium deficiency)?

I can provide pics if needed!

Thanks in advance for your help!
 

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Just my two cents...and it is kind of my soap box...

It won't matter. Metricide/Excel is not a good source of carbon for plant uptake. But as an algicide it works!
With your options, I would leave the lights alone if it's working for you then dose Metricide at 5pm when you get home.

Also, it has been known to cause problems with Vals. Some people see no problems, others get meltdown.

In terms of Flourish, if all is going well, I would not change a thing!!
 

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The two standard 20 gallon tanks are 24 inches long, 17 inches high, and 30 inches long, 13 inches high. Which do you have? What is the length of your light fixture? Without that information it isn't possible to guess how much light you are using, so it isn't possible to figure out what you need to supply the plants with the nutrients they need.

If you just want to know about dosing Metricide, I suggest dosing it in the morning before you go to work, whether you use a split lighting schedule or not. It remains in the water in a useful concentration for up to about 24 hours, so you lose little by dosing it before the lights come on. I hope you didn't mix in the little package of activator?
 

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From the Glut handbook....

In the aerobic system, active glutaraldehyde had a half-life of approximately 10.6 hours and was completely metabolized after
48 hours. During this period, the radiolabeled glutaraldehyde was found to be converted first to glutaric acid, and then further
metabolized to carbon dioxide.

Under anaerobic conditions, the active glutaraldehyde concentrations decreased rapidly in the water with a half-life of 7.7 hours,
and was completely metabolized in 3 days (see Scheme 2).The intermediate metabolite in the anaerobic water study was
5-hydroxypentanal. This intermediate was found to be further metabolized to 1,5-pentanediol.
 

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Discussion Starter · #5 · (Edited)
The two standard 20 gallon tanks are 24 inches long, 17 inches high, and 30 inches long, 13 inches high. Which do you have? What is the length of your light fixture? Without that information it isn't possible to guess how much light you are using, so it isn't possible to figure out what you need to supply the plants with the nutrients they need.

If you just want to know about dosing Metricide, I suggest dosing it in the morning before you go to work, whether you use a split lighting schedule or not. It remains in the water in a useful concentration for up to about 24 hours, so you lose little by dosing it before the lights come on. I hope you didn't mix in the little package of activator?
It's 24 inches long, 15.5 inches high, 13.5 inches wide

The light is the 18 inches model (for 18-24" tank)

According to current USA, this light provide 36 PAR at 12", and 28 PAR at 28". This is straight under the light so I'm not sure exactly how much light will reach the front and the back of the tank (+/- 6 inches each way).

I have 2 1/2 inches of flourite substrate, and the light is hanging 1 inch above water, 14 inches above substrate.

From what I read, Excel/metricide doesnt stay 24 hours in the tank. It was more in the 12 hours range (probably less according to Ichy's previous post).

This is why I was thinking about the split photoperiod schedule... This was what I thought to be the best compromise...

Bump:
From the Glut handbook....

In the aerobic system, active glutaraldehyde had a half-life of approximately 10.6 hours and was completely metabolized after
48 hours. During this period, the radiolabeled glutaraldehyde was found to be converted first to glutaric acid, and then further
metabolized to carbon dioxide.

Under anaerobic conditions, the active glutaraldehyde concentrations decreased rapidly in the water with a half-life of 7.7 hours,
and was completely metabolized in 3 days (see Scheme 2).The intermediate metabolite in the anaerobic water study was
5-hydroxypentanal. This intermediate was found to be further metabolized to 1,5-pentanediol.
There is something I'm not sure to understand :

Glutaraldehyde has a half life of 10.6 hours THEN is converted to glutarid acid and THEN metabolized to carbon dioxide (which is useful for plants). So the period where Carbon Dioxide is available for plants is anywhere from 10 hours after glutaraldehyde is added to the tank and 48 hours where it is completely metabolized??? If so it just doesn't matter when you add it to the tank...

Am I reading this right? or is it the opposite, carbon dioxide is available only during the first 10.6 hours or so?
 

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It's 24 inches long, 15.5 inches high, 13.5 inches wide

The light is the 18 inches model (for 18-24" tank)
LED lights don't produce much light intensity beyond the end of the light. The drop off at the end is significant, and beyond the end it drops off a lot more. A 24 inch long tank should have a 24 inch long LED light.
According to current USA, this light provide 36 PAR at 12", and 28 PAR at 28". This is straight under the light so I'm not sure exactly how much light will reach the front and the back of the tank (+/- 6 inches each way).

I have 2 1/2 inches of flourite substrate, and the light is hanging 1 inch above water, 14 inches above substrate.
You probably have about 35 PAR at 14 inches, which is low light, but at the high end of low light.
From what I read, Excel/metricide doesnt stay 24 hours in the tank. It was more in the 12 hours range (probably less according to Ichy's previous post).

This is why I was thinking about the split photoperiod schedule... This was what I thought to be the best compromise...

Bump:

There is something I'm not sure to understand :

Glutaraldehyde has a half life of 10.6 hours THEN is converted to glutarid acid and THEN metabolized to carbon dioxide (which is useful for plants). So the period where Carbon Dioxide is available for plants is anywhere from 10 hours after glutaraldehyde is added to the tank and 48 hours where it is completely metabolized??? If so it just doesn't matter when you add it to the tank...

Am I reading this right? or is it the opposite, carbon dioxide is available only during the first 10.6 hours or so?
Glut has a half life of almost 12 hours, so its concentration is still at half the original at about 12 hours, and reduces to near zero in 24-48 hours. It doesn't work by providing CO2. It is a compound that plants can use in place of CO2, but not very efficiently. For low light it is a reasonably good substitute for CO2.

My 65 gallon tank also has about 35-40 PAR lighting, and I use Metricide too, at between 1 ml and 2 ml per 10 gallons of water. (I dose around 6-7 ml for aboout 55 gallons of water.) I also dose NPK and chelated iron, in addition to a regular trace mix. http://www.plantedtank.net/forums/1...fertilizing-65-gal-low-medium-light-tank.html describes how I decided how much of what to dose.
 
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