Fish Quiz

[eaglesaquarium]

Apart from aesthetics, why is ocean rock used in African cichlid set ups?

 
 

to raise the PH

 
I'd add that in addition to merely increasing the pH, it is also useful in raising the kH, which is even more important for the cichlids.  They require not just high pH, but hard water.  You need to consider the kH, and even the gH and TDS as well. 

 

[the_lock_man]

Re the guppy question, I would add that in a large enough group of guppies, it is OK to keep them in 1:1 ratio.

 

[Baccus]

Also relating to the guppy question.... when keeping males and females together in large groups its impossible to keep even a 1:1 ratio since the females will constantly be giving birth with the guppy numbers ever increasing

.

 

[508]

what is the smallest crypt?

 

[daizeUK]

cryptocoryne parva

 

[508]

yep
 
I bought some myself but I'm almost sure I won't be able to grow them, half of them barely get any light because the amazon sword keeps blocking out light.

 

[daizeUK]

Nah I failed at growing C. parva too.
 
Okay let's mix it up with a complicated chemistry/maths question.  You're gonna hate me for this (unless you love this stuff, like me!)
 
Given the atomic weights listed below, calculate how many milligrams of Potassium Nitrate (KNO3) I would need to fertilise a 
 
100L tank with 10ppm of nitrate.
 
Potassium - 39.1
Nitrogen - 14.01
Oxygen - 16
 
For extra bonus geek points, how many ppm of potassium would this give you?

 

[Mamashack]

Oh dear my chemistry shutters have descended! lol
Interested to see the answer tho!

 

[eaglesaquarium]

10 ppm is basically equivalent to 10 mg/L of nitrate.  As 1g/ml is the density of water, and so 1mg/L would be 1ppm.
 
Potassium nitrate is 101g per mole.  62grams of which is nitrate.
 
Adding 62 grams of nitrate would raise the concentration in 100L to 0.62g/L or 620mg/L or 620ppm nitrate.  That's 62 times too high.  So dividing by 62 would bring 10ppm nitrate.  Which means dividing the 101g by 62 would bring the appropriate concentration... 1.62 grams of potassium nitrate would need to be added to achieve the requested concentration of 10ppm nitrate.
 
If you are interested that would be 39grams of potassium would make the concentration in 100L to 0.39g/L or 390mg/L dividing by the 62 as above, then the concentration of potassium would be 6.29 ppm.

 

[daizeUK]

Perfect answer!
 
I did it by adding up the atomic weights and got this answer: 
1630.5mg of KNO3 gives 10ppm of nitrate and 6.3ppm of potassium in a 100L tank.
Any small differences in our answers would be because I arrived at a molecular weight of KNO3 as 101.11 and 62.01 for nitrate.  Nobody would weigh it that accurately anyway!

 

[eaglesaquarium]

Perfect answer!
 
I did it by adding up the atomic weights and got this answer: 
1630.5mg of KNO3 gives 10ppm of nitrate and 6.3ppm of potassium in a 100L tank.
Any small differences in our answers would be because I arrived at a molecular weight of KNO3 as 101.11 and 62.01 for nitrate.  Nobody would weigh it that accurately anyway!

I'm a physics guy, not a chemistry guy, so that must account for my approach. As to the significant figure differences, my scale doesn't go beyond 2 decimal places, and even the last digit changes so much with air currents in the room it's basically a guess.

Silly wiggly numbers.




Why do Christmas Island crabs march to the sea every year, if they are land crabs that can't swim and can drown in a small amount of water?

 

[Ch4rlie]

To breed

 

[DrRob]

Ahhh, it's gotta be for the beach barbecue, it's legendary!
 
The crab claws are amazing.

 

[daizeUK]

Lol!  

 

[eaglesaquarium]

To breed
 

 
 
Close enough.
 
To learn more:
http/www.christmas.net.au/experiences/red-crab-migration.html