2 issues- Algae and Dying torch

[Masonjames]

Originally Posted by Reef Pilot

Gawd,... I have better things to do,... but here goes one more time.

Start with a barrel of 100 apples. Change 10% volume (incl that percentage of oranges from the previous day) every day for 10 days with oranges. (Of course, after a day you will have to start slicing the oranges and apples a bit to get the right proportions...)

At the end of 10 days, in the barrel, you will still have 34.86784401 apples and only 65.132156 oranges. Oranges can represent new water, and apples the old water nutrients.

And if you change 100% of the apples with the oranges in one change, you would have all oranges and no apples.



And daily changes over a longer period of time, just makes it worse... Not sure how else to explain it. If this doesn't do it, I give up...

Originally Posted by Reef Pilot

.

Think of it another way, and maybe might make more sense to you. If you exchange 10% of your water each day over 10 days, you will have changed 100% of your volume. But you still have some of your original water and nutrients present because of your daily mixing and dilution. However, if you change 100% of your water in 10 days, for sure you will have a complete exchange of nutrients and no old water.

Those exact same principles of mixing and dilution apply to any percent changed so I don't understand the differnce your trying make. With your apple to oranges comparison, you are neglecting to apply the very principles you brought up originally. You are applying the rule that you are removing 100% of whatever percent of apple you are removing. But you've neglected to apply your mixing and dilution rule that once In the barrel, those apples and oranges must become so thoughly mixed they become for the most part unrecognizable from each other. Now pull out a handful and calculate from the slurry how many apples and how many oranges.
If you change x% volume biweekly with a single water change, you will have changed x% of your systems volume monthly. But you still have some of your original water and nutrients present because of mixing and dilution. If you change x% volume daily you will have change x% volume of your systems volume monthly. But you still have some of your original water and nutrients present because of mixing and dilution. Unless your doing a single 100% change, your still leaving behind old water and nutrients and removing a percentage of the previous change. I guess one could consider 2 week old water changed already spoiled removing the potential to remove a percent of brand spanking new water by changing daily. But those principles of mixing and dilution are actually what sorta makes the math work on a small scale change as the mixing and dilution happeneds over a much larger body.

[Reef Pilot]

Don't know what else to say.... Do the math for yourself and you will see. You can use any example or proportion you want. The point is the same. And that is that changing the same vol of water less frequently gives you a bigger bang for the buck with nutrient exchange.

I am not arguing that frequent water changes are bad. It's just that you need to do bigger volumes to make up the difference over time. In fact, if your tank has high nutrients, a big water change is not as good because of the possible rapid composition change of your parameters. But that is another issue... My point above is just about the math...

[Kellyscoral]

Hmmm - I may have had one too many tequila shots cause this is all clear as mud in my brain!!