Why do we do water changes so religiously if we can remove the nitrates?

[Randy Holmes-Farley]

Thought I'd give you my 2 cents - not to argue but because its an interesting discussion. Thanks for that study - it was hard to read - but -- which they do a good job summarizing the difficulties of this study - like you did above) - But those are BIG problems - so its hard to make any conclusion (which they also said) - right?

Here are the conclusions that I read at the end of the article:

• most synthetic sea salts do not have high levels of many trace elements,
• natural seawater is not automatically a safe alternative to synthetic sea salts when it comes to comparing amounts of trace elements in the two solutions,
• past comparisons of synthetic sea salts to natural seawater are flawed because they compared synthetic sea salts to a hypothetical natural seawater that is not available to the majority of marine hobbyists, and
• synthetic sea salts are quite acceptable for long-term use in marine aquaria when considered from the viewpoint of not adding detrimental concentrations of trace elements to the system.

To me - these suggest - that you're correct - doing water changes does not supply trace elements to a great degree (in THESE salts) - there are others - that claim to have trace elements identical to seawater (at least the ones that they feel important - Brightwell neomarine for example). Second - To me the problem with a no-water change system is not low trace elements - its build up of trace elements - or am I totally off base.

The problem with trying to talk about trace elements in all sorts of different contexts is that there is little to no evidence of what levels are desirable and/or needed. Aside from a few examples, such as iron in parts of the ocean where it is known to be a limiting factor to phytoplankton growth even at natural levels, we have no idea with, say, manganese, how much is needed.

Is a NSW level of manganese "needed" in a reef tank?

Is ten times less still plenty? 100x less?

Is more than a natural level of manganese useful?

Multiply that by, say, 30 trace elements and an almost infinite way of binding these to organics that modify bioavailability, and the problem becomes immense. Water changes might easily maintain 100x less than the levels in the salt mix. Maybe 10x less. Likely not 1x.

But, of course, foods add all trace elements too.

There is no simple answer.

 

[MnFish1]

Maybe I'm due for another ICP test? I think the risks are inverted for the two techniques. With water changes you risk depletion. With dosing, the worse evil is having buildup and runaway. I guess the good news is that if you are dosing close to the consumption rate the runaway problem typically happens slowly (in either direction).

Do they run away at different rates? That is the 100k question. Lets hope so, I would rather dose less trace elements than more. ;-).

My idea - is that with trace elements - or feeding the fish - you're adding trace elements - water changes means that (since you're not 'dosing them' - they will not accumulate over time.

 

[jda]

Maybe I am going back too far, but what ever happened to the advice to not dose anything that you cannot test for? Even thought this may be dogmatic and not in line with the current thinking to advise somebody to get the supplement-of-the-day to cure some/all ills, I would still suggest that people follow this.

 

[Randy Holmes-Farley]

Maybe I am going back too far, but what ever happened to the advice to not dose anything that you cannot test for? Even thought this may be dogmatic and not in line with the current thinking to advise somebody to get the supplement-of-the-day to cure some/all ills, I would still suggest that people follow this.

Won't work with some trace elements, unless you intentionally dose above NSW levels. Iron, for example. ICP (Triton) cannot detect NSW levels.

I suspect Red Sea only recommends massive overdoses of iron to ensure their kit can measure it. lol

 

[jda]

I suspect Red Sea only recommends massive overdoses of iron to ensure their kit can measure it. lol

Of course this is not JUST it... they want to sell the supplements as well as the test kits.

 

[Greg Gdowski]

Nicely stated. I was just trying to find something to read on this.

The problem with trying to talk about trace elements in all sorts of different contexts is that there is little to no evidence of what levels are desirable and/or needed. Aside from a few examples, such as iron in parts of the ocean where it is known to be a limiting factor to phytoplankton growth even at natural levels, we have no idea with, say, manganese, how much is needed.

Is a NSW level of manganese "needed" in a reef tank?

Is ten times less still plenty? 100x less?

Is more than a natural level of manganese useful?

Multiply that by, say, 30 trace elements and an almost infinite way of binding these to organics that modify bioavailability, and the problem becomes immense. Water changes might easily maintain 100x less than the levels in the salt mix. Maybe 10x less. Likely not 1x.

But, of course, foods add all trace elements too.

There is no simple answer.

The problem with trying to talk about trace elements in all sorts of different contexts is that there is little to no evidence of what levels are desirable and/or needed. Aside from a few examples, such as iron in parts of the ocean where it is known to be a limiting factor to phytoplankton growth even at natural levels, we have no idea with, say, manganese, how much is needed.

Is a NSW level of manganese "needed" in a reef tank?

Is ten times less still plenty? 100x less?

Is more than a natural level of manganese useful?

Multiply that by, say, 30 trace elements and an almost infinite way of binding these to organics that modify bioavailability, and the problem becomes immense. Water changes might easily maintain 100x less than the levels in the salt mix. Maybe 10x less. Likely not 1x.

But, of course, foods add all trace elements too.

There is no simple answer.

If you understand it why would you assert that two scenarios with very different outcomes " behave *exactly* the same way "?

Which assertions are those specifically?



I think that it is a wrong assumption since trace consumption could vary wildly depending on the organisms we have in our tanks (for example we know sponges consume more silicates) but that doesn't mean it's not a useful assumption. Rules of thumb are often the best way to control complex systems even when they are based on incorrect models. obviously it works well enough but that leads to the obvious question, How do you not get depleted elements or runaway accumulation if, as we know, those consumption rates vary by organism? Does consumption vary with concentration? Do the trace elements fall out of solution somewhere? are we being sold what we're told? or has TM figured all this out and has built in some kind of safety margin which at normal dosing amounts guarantees your levels won't go too far wrong. I admit, I use this method of dosing. I dose home brewed all-for-reef which does much the same thing. Though I also change water at ~15% per week which as the models we agree on show would manage reasonable under and over dosing.



Does that matter or is it a distinction without a difference? natural seawater also has higher levels of industrial pollutants. I'm not sure what we can conclude from this.

But this is by the by. The point that I made is that it is cheaper and easier to manage these things at smaller water volumes by simply changing water regularly rather than testing for and dosing all of those elements in precise quantities which is the normal implication if you decide to stop changing water. Not testing and not changing water will always be cheaper but it doesn't sound like a high probability path to success.

I don't disagree. One would think it would vary wildly. I just haven't seen it. Doesn't mean I'm right. If it varied wildly, one salt might work in one circumstance where another wouldn't work at all. Very much open questions. I don't think I ever advocated for no testing.

I don't think the elements fall out of solution (at least I hope not!). That said, it is more like putting 5 grams of salt in a cup of sugar --- mixing it --- taking half and hoping you have recovered 2.5grams of salt. =

 

[Sm51498]

I don't disagree. One would think it would vary wildly. I just haven't seen it. Doesn't mean I'm right. If it varied wildly, one salt might work in one circumstance where another wouldn't work at all. Very much open questions. I don't think I ever advocated for no testing.

One of the major problems we have In this hobby is survivorship bias. We look at the successful systems and glean what lessons we can from them. Of course. We very often ignore failures which ime can be almost indistinguishable from the successes in terms of methodology. I think what we're poking at here is that poorly understood difference between those successful reefs and some failures. There are factors at play which just work for some of us and then fail spectacularly for others. A lot of unknown variables here.

I know you wouldn't advocate no testing. Merely stating the obvious that there is a third course of action here that sometimes works for some people.