Happy tank, skip a water change?

[grouper therapy]

Russ-IV;1068500 wrote: my example was given to show the insignificance of a 10% wc even done weekly.
it doesnt move much.

that goes for replenishment as well. it was just easier to give the example based off export rather than replenishment due to the 10% difference of a fresh salt batch vs what your tank consumed.

If your nutrient export is =/> than your your nutrient import than the 10% weekly water change will get you to 47% purity in 6 weeks instead of 4 weeks.
In your scenario above it doesn't matter which system you use, your system would eventually be an ultra high nutrient.
For example: second month starting with 10ppm and adding 20ppm would give you 30ppm at 3rd month reduce 50% now you are at 15ppm plus the 20ppm , 4th month 37 pmpm. Not a good pattern.
That said I think I understand what you were trying to say that 5 10% wc are not as effective as 1 50% wc and you are correct. But it is not near the difference you showed above . Those numbers skew the actual difference.
There is a WC calculator over at reef central that will help you see the difference.The assumption has to be made though that your wc% is =/> than the nutrient introduction.

 

[grouper therapy]

Four 15% weekly water change will export almost the exact ppm as 50% monthly water change will in 4 weeks

 

[russ-iv]

grouper therapy;1068501 wrote: If your nutrient export is =/> than your your nutrient import than the 10% weekly water change will get you to 47% purity in 6 weeks instead of 4 weeks.
In your scenario above it doesn't matter which system you use, your system would eventually be an ultra high nutrient.
For example: second month starting with 10ppm and adding 20ppm would give you 30ppm at 3rd month reduce 50% now you are at 15ppm plus the 20ppm , 4th month 37 pmpm. Not a good pattern.
That said I think I understand what you were trying to say that 5 10% wc are not as effective as 1 50% wc and you are correct. But it is not near the difference you showed above . Those numbers skew the actual difference.
There is a WC calculator over at reef central that will help you see the difference. the assumption has to be made though that you %? is =/> than the nutrient introduction.

6 water changes at 10% being 47% purity?
lets test that. we will assume you do 6 10% water changes the same day....

tank has 100ppm nitrate (for ease of calculation)

wc1: 90ppm
wc2: 81ppm
wc2: 72ppm
wc3: 65ppm
wc4: 58ppm
wc5: 53ppm
wc6: 47ppm

that is if you did them all on the same day. we didnt even get to net increases or decreases of nutrients/trace elements.

lets say the tank is 100 gallons.
you burned up 60 gallons netting 47ppm

if i did the same 60 gallons at once i get 40ppm.


also... water changes will always net you with nutrients. you can not take less than 100% and hit 0.

so a lot of flaws in your logic.

 

[grouper therapy]

Russ-IV;1068505 wrote: 6 water changes at 10% being 47% purity?
lets test that. we will assume you do 6 10% water changes the same day....

tank has 100ppm nitrate (for ease of calculation)

wc1: 90ppm
wc2: 81ppm
wc2: 72ppm
wc3: 65ppm
wc4: 58ppm
wc5: 53ppm
wc6: 47ppm

that is if you did them all on the same day. we didnt even get to net increases or decreases of nutrients/trace elements.

lets say the tank is 100 gallons.
you burned up 60 gallons netting 47ppm

if i did the same 60 gallons at once i get 40ppm.


also... water changes will always net you with nutrients. you can not take less than 100% and hit 0.

so a lot of flaws in your logic.

No flaws at all . You just proved what I was saying, we both came pretty close to the same export. You at 40 ppm and me at 47ppm. Like I said it is close.
Fwiw . This is not my logic at all , I do agree with it, but it was obtained from the reef central w/c calculator.
That 7ppm difference is worth it to some not to shock their system.
I like 15% weekly w/c which happens to maintain my system at near o nitrates

 

[grouper therapy]

Like I said earlier I agree with you that is is 10% w/c are not as effective as 50% just not as great as your first scenario. that's all.
Like I mentioned earlier the assumption was made that nutrient export was =/> than import.

Have you had your coffee yet?

 

[russ-iv]

grouper therapy;1068502 wrote: Four 15% weekly water change will export almost the exact ppm as 50% monthly water change will in 4 weeks

this is not true.

take 2 tanks... 100 gallons. 100ppm nitrate.

both tanks increase 5ppm nitrate a week

me: week 4 50% change nets 60ppm nitrate (120 * 50%)
you:

wc1: 105*.15=89
wc2: 94 *.15=80
wc3: 85 *.15=72
wc4: 77 *.15= 66

66 > 60

lets keep things in context. if you wanted stability, you wouldnt change anything. if you are replenishing or removing stuff. then keep the "over-time" context of a tank gradually increasing or decreasing from the mean you are attempting to keep.

 

[grouper therapy]

Russ-IV;1068509 wrote: this is not true.

take 2 tanks... 100 gallons. 100ppm nitrate.

both tanks increase 5ppm nitrate a week

me: week 4 50% change nets 60ppm nitrate (120 * 50%)
you:

wc1: 105*.15=89
wc2: 94 *.15=80
wc3: 85 *.15=72
wc4: 77 *.15= 66

66 > 60

lets keep things in context. if you wanted stability, you wouldnt change anything. if you are replenishing or removing stuff. then keep the "over-time" context of a tank gradually increasing or decreasing from the mean you are attempting to keep.

So you exported 60 and me 66?

 

[russ-iv]

grouper therapy;1068508 wrote: Like I said earlier I agree with you that is is 10% w/c are not as effective as 50% just not as great as your first scenario. that's all.
Like I mentioned earlier the assumption was made that nutrient export was =/> than import.

Have you had your coffee yet?

I read that wrong. I do need coffee more i think about it lol

Anyway...

the reason I bring this up is because I have a 300 gallon system. Changing water is no easy feat sometimes. even with a 100 gpd & booster pump RO unit.

call it lazy, but it is easier to do 1 150 gallon water change every 3 months than every weekend doing a 30 gallon change.

My wife's 40 breeder cannot get away with that due to the size of her tank. Generally a wc is needed every 2nd week at 25%.

like i said, i understand why people follow the 10% wc cadence. It may not be for everyone.

 

[russ-iv]

grouper therapy;1068514 wrote: So you exported 60 and me 66?

you have 66 i have 60

you exported a total of 54 ppm nitrate
i exported 60 ppm nitrate

 

[grouper therapy]

Russ-IV;1068517 wrote: I read that wrong. I do need coffee more i think about it lol

Anyway...

the reason I bring this up is because I have a 300 gallon system. Changing water is no easy feat sometimes. even with a 100 gpd & booster pump RO unit.

call it lazy, but it is easier to do 1 150 gallon water change every 3 months than every weekend doing a 30 gallon change.

My wife's 40 breeder cannot get away with that due to the size of her tank. Generally a wc is needed every 2nd week at 25%.

like i said, i understand why people follow the 10% wc cadence. It may not be for everyone.

I totally agree. I did 20% weekly W/C on my big system just to keep up with the nutrient level.
Now go pour that cup!

 

[axio]

Where did the 10% come from? Weekly yes... but people should do what ever percentage they need to cut the nitrates/nutrients down properly. I usually do 20% water changes a week and a test from time to time to make sure I'm still on track. With so many variables in play I think it is dangerous assuming a certain percentage is enough for all tanks. One truly needs to test and get a feel for what their systems needs. In my opinion some tanks might be perfectly fine on 10% weekly... others might need 30% water changes weekly. Heck we have some overloaded FOWLR tanks out on the field that need 50% weekly to keep up with them.

I think no matter the percentage needed to be done, I feel it is still more beneficial to do them weekly versus monthly. There are too many trace elements that we don't test for that are replenished with these water changes to prolong them very much in my opinion.

Jakub

 

[russ-iv]

aXio;1068524 wrote: Where did the 10% come from? Weekly yes... but people should do what ever percentage they need to cut the nitrates/nutrients down properly. I usually do 20% water changes a week and a test from time to time to make sure I'm still on track. With so many variables in play I think it is dangerous assuming a certain percentage is enough for all tanks. One truly needs to test and get a feel for what their systems needs. In my opinion some tanks might be perfectly fine on 10% weekly... others might need 30% water changes weekly. Heck we have some overloaded FOWLR tanks out on the field that need 50% weekly to keep up with them.

I think no matter the percentage needed to be done, I feel it is still more beneficial to do them weekly versus monthly. There are too many trace elements that we don't test for that are replenished with these water changes to prolong them very much in my opinion.

Jakub

I believe the tanks running the triton method (no water changes) would disagree with the "weekly" cadence.
Not all tanks are the same. The corals will tell you more imo.

Dont get me wrong. Do what works for your tank. I just think some blanket statements could use some refining.

 

[doctorgonzo788]

I use Zeovit Zeostart on this tank and have been targeting a low non-zero reading (I hate color matching test kits, is it 2? 5? 10? Ugh).

I'm really glad this thread has sparked some lively discussion.

What are everyone's thoughts on nutrients in softy tanks vs SPS only tanks?

 

[jennm]

The solution to pollution is dilution.

The 10% comes from a basic rule of thumb for most lightly to moderately stocked tanks. Everyone's mileage may vary.

Changing a small amount of water more frequently, changes more water over time, and keeps parameters more stable than doing a huge water change at a longer interval, and having a longer period of time where the water quality degrades.

Testing is a must. One has no idea whether the water changes are effective if they aren't monitoring parameters. Goodness knows over the years I've tested samples and found horrific parameters in 'maintained' tanks where people changed water, but didn't bother checking to see if it was 'enough'.

Jenn