Water change too much?

blaxsun · Dec 13, 2022

brandon429 said:
and its full of perfect healthy corals too

If you mean my tank, for the most part - yes.

Crustaceon · Dec 13, 2022

NormanB said:
OK, the dinos are not a real problem, so perhaps the main thrust of this thread is...

Is weekly 12% water changes in my 80 gallon system too much?

I'd say yes. If you're experiencing dinos, cut back to a weekly 5% change and give it a month to re-evaluate. Nothing gets fixed quickly in this hobby. What you're waiting for is a balancing of not just nutrients in the system, but the biome that consumes them. If you find the right balance, beneficial bacteria WILL outcompete dinos and they'll go away seemingly out of nowhere. You just want to avoid passing up that balancing point by doing too much too fast.

Dom · Dec 13, 2022

NormanB said:
Dom, what is you goal by doing 20% weekly changes?

Thanks

20% weekly water changes accomplish:

Nutrient Export - It is one way we can keep nitrates and phosphates down to acceptable levels.
Element Replenishment - Calcium, carbonate, magnesium depleted through coral consumption are added back to the water, allowing corals to continue receiving the elements necessary for for it to survive and thrive.

But remember, they have to be faithful weekly changes.

Why?

Because in this hobby, stability is paramount. This helps preventing erratic swings in parameters.

As an example, if you have a calcium consumption rate of 40 per week, and your starting calcium after the water change is 430, you can expect your calcium to be about 390 at the 1 week mark when you are making your next water change.

This means your calcium will always be in a good range for healthy coral growth.

But if you were to wait 3 weeks between changes, you calcium will now have a range of 120 points and your calcium will be between 440 and 310. That is a lot of time for corals to spend in low calcium.

In general, I feel fluctuation in element levels should never range outside the industry accepted standards. Although, there are exceptions.

Randy Holmes-Farley · Dec 14, 2022

Dom said:
But if you were to wait 3 weeks between changes, you calcium will now have a range of 120 points and your calcium will be between 440 and 310. That is a lot of time for corals to spend in low calcium.

I do not think that is possible unless you are supplementing alkalinity and not calcium . To get a decline in calcium of 120 ppm, alkalinity would have to decline by more than 17 dKH.

Dom · Dec 14, 2022

Randy Holmes-Farley said:
I do not think that is possible unless you are supplementing alkalinity and not calcium . To get a decline in calcium of 120 ppm, alkalinity would have to decline by more than 17 dKH.

I'm sure you are correct. It was a labored effort to try and explain how longer intervals between water changes cause larger fluctuations in water chemistry.