effectiveness of water changes

[leftovers]

I made up a quick excel spreadsheet. I made it quite simple. We add 10 parts of X every week. I then had 4 options for water changes to remove X: 10% every week, 25% every week, 25% every 2 weeks, 50% every month and 50% every 2 months.

After 2 years: 10% weekly = 90 parts X, 25% weekly = 30 parts X, 25% 2 weeks = 60 parts, 50% monthly = 60 parts, and 50% every two months = 80 parts.

The problem with just calculating your dilutions is you are not counting what you are constantly adding.

Not really, and is the case you can tweak the numbers to show whatever you'd like the audience to see.

In this thread the discussion was primarily about dilution from static volume

After 1 year your 10% + 10 part addition results in 90 parts for 52 water changes, for 50% its only 78.75 parts for 6 water changes.

Keeping things = then doing 50% every week you start with 10 parts and end with 10 after 52 changes.

You will always have a dimishing margin of returns with any water change short of 100% where you are constantly adding things.

And if we were to futher analyze this, what kind of labor would rather be doing with your tank? Constant tweaking every week? or Monthly or bi monthly adjustments?

 

[spsmike]

I believe he is somewhat right here guys. Maybe not in the context of noobs but for us advanced guys.

Most of the salt mixs I know of actually test very high in trace elements. Its something to think about, but for a more accuracy someone would need to actually test the consumption rate of the trace elements.

Ok say my salt mix mixs at 1300 in mag and I do a one gallon water change on a ten so thats 1/10th.

Mag is 1100 in tank.

mag in mix is 1300.

1300 diluted by 10 is 130.

So it would be (1100 x 9 ) + (1300 x 1 ) / 10 = 1120

So that would raise the ppm of mag that instant 20 ppm. If the consumption rate was higher then 20 ppm or the mix mag rate was higher then less or more of a water change would be needed.

 

[Anonymous]

Just my opinion but avoiding water changes just because it doesn't perfectly fix all water parametersisn't good common sense. If it improves water conditions then why isn't it worthwhile?

Mg is typically consumed at a very low rate so I would think it's a good candidate for being maintained with water changes.

Ca and Carbonate typically have too high a consumption rate to be maintained by water changes and water changes can actually lower these levels. As a result they should be dosed seperatly.

As far as pollution, well, if a water change remove 20% of the pollutants then why wouldn't it be worthwhile? Is it better to keep all the pollution just because a water change won't completely fix the problem?

I look at a system as the sum of it's parts. Each part plays a role. I believe that looking for the "big hit" that solves all problems is a mistake.

 

[spsmike]

I dont believe he is saying to not do water changes. I beleive he is trying to say not to do them thinking your going to resolve any and all trace elements issues.

Mag was used as an example.

 

[Anonymous]

I dont believe he is saying to not do water changes

yes he is, bob advocates no maintenance tank because tap water and macros will maintain it for you..You havent been following Bobs posts in other topics...He believes if you use macros, low light, low flow, you can maintain a tank just like yours mike, full of sps..he has yet to completely or even partially understand the demands of a reef tank..and unfortunately for him, he doesnt want to..My belief is, that he is very lazy and wants to "create" a new method of reef keeping (which by the way is scientifically not sound)

 

[spsmike]

Ok well if thats the case then thats a judgement of his reef keeping however not his thread here right?

This is a pm conversation I would like to present.

think your numbers are right on the thread however I think you forgot to calculate the natural removal of nutrients via bacteria deep within live rock and dsbs ect that work in conjunction. So I dont think its right however its a creative thought and its thoughts like that, thats needed in the hobby.

I personally think that having general rules for reef tanks is crazy being that the array of corals we keep come from so many environments in the wild.

Your thread did what it was supposed to. Stir up creative thought. One of the reasons I have a debate forum on my board.

Absolutely!!!!!!

And the equations in my very first post stated that is was to evaluate the effectiveness of water changes. to do that just consider the water changes. As you and I know other things are needed. And when those other things are implemented then water changes are not needed and probably detrimental. But to arrive at that conclusion one must first evaluate such statements as "you need to do water changes to maintain trace elements". Which is simply not correct as demonstrated by the equations presented.

Bob

 

[Anonymous]

I dont believe he is saying to not do water changes.

He is.

I beleive he is trying to say not to do them thinking your going to resolve any and all trace elements issues.

I don't believe anyone has argued otherwise.
This is one of the bob issues - he presents ideas as if he is the first one to think of them while at the same time arguing against a dogma that doesn't actually exist.

 

[Anonymous]

Ok well if thats the case then thats a judgement of his reef keeping however not his thread here right?

Wrong, its another way of him propagandizing his sloppy methods...

 

[wade1]

Enough guys. Back to topic....

I have never seen a reason against water changes myself. Salt mixes have less undesirables (in general) than even atmospheric deposition. The one chemical that is in most salt mixes that it would be nice to avoid is phthalates (plasticizers)... they cause issues in sex determination, although there are many different kinds.

I ALWAYS push people to do biweekly water changes of 30%. Its a good balance between what people can manage and a good amount to keep up with water quality.

 

[Anonymous]

Is the phthalates from the container/bag the salt mix is in, or it is from the processing, or it is added purposely?

 

[Anonymous]

Bob worte: But to arrive at that conclusion one must first evaluate such statements as "you need to do water changes to maintain trace elements". Which is simply not correct as demonstrated by the equations presented.

I don't think anyone says anything like 'you need to do water changes to maintain trace elements'.

 

[wade1]

Is the phthalates from the container/bag the salt mix is in, or it is from the processing, or it is added purposely?

It is not added purposely. It leaches out of either the processing or the buckets themselves (I would daresay the buckets). I would also bet that skimming heavily and using activated carbon would remove much of them from the system fairly quickly (aside from the portion taken up by critters).

 

[Anonymous]

Is the phthalates from the container/bag the salt mix is in, or it is from the processing, or it is added purposely?

It is not added purposely. It leaches out of either the processing or the buckets themselves (I would daresay the buckets). I would also bet that skimming heavily and using activated carbon would remove much of them from the system fairly quickly (aside from the portion taken up by critters).

Its the buckets!