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Tunze DOC 9430 - best skimmer money can buy? Impact on phosphates?

Alexander1312

Supporting Member
Has anyone tried this one yet?

I believe someone here claimed that skimmer cannot reduce phosphates significantly / or at all from the water.

I know from several credible sources that this skimmer was able to bottom out previously high phosphates in larger tanks (300 gallons up). Any thoughts?

I cannot continue doing 30% weekly water changes, and I am looking for a serious solution to this problem (which, ideally, does not involve LC).

 
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I believe the science of skimmers has been around a long time so what about Tunze’s skimmer allows it to skim phosphates better than other skimmers. I have not been in the hobby long but it looks like the tech upgrades to skimmers in the last few years have all been pretty basic: DC motor, more controlability via an app, neck cleaner, light up skimmer body, sensors which help prevent overflow, auto drain feature, etc. None of these relate to the basic science behind the skimming process itself.
 
I believe the science of skimmers has been around a long time so what about Tunze’s skimmer allows it to skim phosphates better than other skimmers. I have not been in the hobby long but it looks like the tech upgrades to skimmers in the last few years have all been pretty basic: DC motor, more controlability via an app, neck cleaner, light up skimmer body, sensors which help prevent overflow, auto drain feature, etc. None of these relate to the basic science behind the skimming process itself.
Agreed. Does the basic science say it does not remove phosphates?

I just wanted to clarify, as I was not clear in my initial post. I am not saying that Tunze skimmers do and other skimmers do not. I know from this skimmer that it does a very good job (apparently), given the pump they put in it (which is why it is so expensive). This started me rethinking skimmers again (and their settings) if phosphate reduction is my core objective.
 
Reefs.com says skimmate has around 4700 ppm phosphate so to me that sounds plausible. But how much are you actually intending to skim lol

 
The science say it does -but whether it removes enough is the question- skimming alone has never gotten my PO4 low enough.

Maybe the beast above does -I can’t say
That is exactly the issue I have. Because it seems they do not, folks are looking for different methods, adsorber, lanthanum, etc.

I always thought setting the skimmer (too) high does not make it more effective as it relates to phosphate (or nitrate for that matter). But it looks like if you are adding one of the most efficient and effective hobby grade pumps available to a skimmer, i.e., the Tunze Stream 3, it might have this effect.

So my thought was that maxing out my existing skimmer’s capabilities might give me a similar effect - I am currently only running it at 50% speed to get the darker skimmate.
 
Reefs.com says skimmate has around 4700 ppm phosphate so to me that sounds plausible. But how much are you actually intending to skim lol

Nice!
 
Reefs.com says skimmate has around 4700 ppm phosphate so to me that sounds plausible. But how much are you actually intending to skim lol

I assume it may be high since it’s like testing concentrated frozen OJ!
 
Here’s a great thread related to your topic I read a while back @Alexander1312
Pay particular attention to Randy Holmes-Farley’s responses since he’s a guru of reef chemistry!

 
Here’s a great thread related to your topic I read a while back @Alexander1312
Pay particular attention to Randy Holmes-Farley’s responses since he’s a guru of reef chemistry!


A guru :). So unless I misunderstand, Grandmaster Randy says, the beloved wet skimming method is a stupid idea?
 
A guru :). So unless I misunderstand, Grandmaster Randy says, the beloved wet skimming method is a stupid idea?
Theres no mention of wet skimming in the thread ? But he will give you his opinion Im sure if you ask him..
My opinion wet skimming just stretches out water changes since the skim mate is really diluted and your removing more water then actual skim. Some reefers just use their skimmers ( wet skimming ) doing smaller water changes more frequently..
 
Theres no mention of wet skimming in the thread ? But he will give you his opinion Im sure if you ask him..
My opinion wet skimming just stretches out water changes since the skim mate is really diluted and your removing more water then actual skim. Some reefers just use their skimmers ( wet skimming ) doing smaller water changes more frequently..
Yes, I know there was no mention of this, I have been just trying to think this further.

Why do you think folks do not just water changes but go the more cumbersome route and use the skimmer for this? This is a genuine question, not a rethorical one. I thought it was to remove extra Nitrate and Phosphate from the water relative to what would be removed by water changes. According to RHF, this would not be achieved by this method. Again, maybe I misunderstood the purpose, so for discussion only.
 
Alex @Alexander1312 I think part of the confusion is just precision of term use. So indulge me giving a little background. Skimmers remove dissolved molecules that adhere to the surface of bubbles because they have one side that is attracted to water and one side that is repelled by it. The term for this is amphipathic. Any water surface, and especially the surface of a bubble, gives them this preferred environment, water on one side and air on the other. By being there, these molecules also stabilize the tiny bubbles so they don’t pop as quickly and make a foam. So a skimmer collects these molecules in the foam. Thicker skimmate has more organics and less water, wetter skimmate has more water. Skimming wet removes more organics per amount of time, at the expense of losing more water. Which is fine if you’re doing a water change with it anyway.

Amphipathic molecules in our tank are mostly organic in origin, and largely proteins. So lots of N and P (as well as C and others). So when you skim you are removing this stuff. If these complex organics are not skimmed out, they break down into stuff like nitrate and phosphate. Nitrate, nitrogen, phosphate and phosphorus themselves are not amphipathic so they don’t skim out directly.

So to say that skimmers don’t remove phosphate is technically correct, they remove the organic waste precursors of phosphate. So effective skimming does lead to lower phosphate levels. Other processes in the tank like coral and algae life/growth also remove phosphate and precursors.

Regarding that specific skimmer, I don’t have any experience or insight. But certainly a more effective skimmer would be more effective at lowering phosphate.
 
Alex @Alexander1312 I think part of the confusion is just precision of term use. So, indulge me in giving a little background. Skimmers remove dissolved molecules that adhere to the surface of bubbles because they have one side that is attracted to water and one side that is repelled by it. The term for this is amphipathic. Any water surface, and especially the surface of a bubble, gives them this preferred environment, water on one side and air on the other. By being there, these molecules also stabilize the tiny bubbles so they don’t pop as quickly and make a foam. So a skimmer collects these molecules in the foam. Thicker skimmate has more organics and less water, wetter skimmate has more water. Skimming wet removes more organics per amount of time, at the expense of losing more water. Which is fine if you’re doing a water change with it anyway.

Amphipathic molecules in our tank are mostly organic in origin, and largely proteins. So lots of N and P (as well as C and others). So when you skim you are removing this stuff. If these complex organics are not skimmed out, they break down into stuff like nitrate and phosphate. Nitrate, nitrogen, phosphate and phosphorus themselves are not amphipathic so they don’t skim out directly.

So to say that skimmers don’t remove phosphate is technically correct, they remove the organic waste precursors of phosphate. So effective skimming does lead to lower phosphate levels. Other processes in the tank like coral and algae life/growth also remove phosphate and precursors.

Regarding that specific skimmer, I don’t have any experience or insight. But certainly a more effective skimmer would be more effective at lowering phosphate.
That is very helpful, John, thank you.

So wet skimming removes more precursors and effectively lowers nutrients overall from the water measured (at a later point) as nitrate and phosphate. It will not remove phosphate and nitrate that have already separated/broken down specifically.

Also, I appreciate the conclusion that a more effective skimmer would be more effective in lowering phosphates, which is the main opinion I am looking for.

Yet, I am still confused about two related things:

1. If the above is correct, why is there a pervasive recommendation in the hobby to go for a right-sized skimmer, specifically one that is not (!) oversized? And often communicated overskimming concerns, which I believe also relate to the fact that trace elements are pulled out from the water disproportionately.

2. What constitutes an ‘effective’ skimmer? A more powerful pump and a larger body? Can I scale the skimmer effect by getting the biggest skimmer that fits into my sump and run this at maximum speed, or are there diminishing returns from this? Is there a limitation with skimming, which, e.g., cannot get the water below a certain N and P level?
 
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