Is Marine Pure releasing Aluminum? And is it haven't any ill effect on your ...

[Scott Campbell]

Regarding alternate Marine Pure blocks made in China, I would think a different manufacturing formula might have a higher concentration of alumina - which would exacerbate the problem - but I would still think the 8.3 threshold would hold true. There are honestly few ceramic items made more cheaply than a flower pot. And few plants as sensitive as orchids. If orchids show no adverse aluminum effects in a flower pot at a pH level below 8.3 I am inclined to believe the Marine Pure blocks will also remain inert below 8.3. But a reef aquarium is certainly more complicated than a flower pot.

That said - these blocks are clearly fired at a very low temperature. Just over quartz inversion. So they are *very* soft and fragile. And ceramic dust is omni-present. I can't begin to tell you how difficult it is to avoid ceramic dust. So there are certainly other ways non-toxic forms of aluminum can show up in a Triton test.

I would be extremely interested to hear your results. I am inclined to continue using my spheres because I am rather confident in my pH measurements and in knowing my pH never gets above 8.2. And I have been very pleased with the benefits of the spheres and have never seen any evidence of aluminum toxicity. But it does give me pause.

 

[Ashish Patel]

My tank setup is 8 weeks old but my PH stays 8.2-8.3. I contribute this more to being close to a large window where more fresh air is coming in.
I'll update if I notice any side effects!

 

[Randy Holmes-Farley]

Regarding alternate Marine Pure blocks made in China, I would think a different manufacturing formula might have a higher concentration of alumina - which would exacerbate the problem - but I would still think the 8.3 threshold would hold true. There are honestly few ceramic items made more cheaply than a flower pot. And few plants as sensitive as orchids. If orchids show no adverse aluminum effects in a flower pot at a pH level below 8.3 I am inclined to believe the Marine Pure blocks will also remain inert below 8.3. But a reef aquarium is certainly more complicated than a flower pot.
.

FYI, there's no threshold effect on solubility of products like alumina. It changes steadily as a function of pH. And the solubility in seawater is going to be very different than in fresh water.

 

[Randy Holmes-Farley]

While I cannot post it here. Aquatic Chemistry concepts by Pankow shows the solubility of aluminum in fresh water as a function of pH (Figure 11.4, page 236), and shows every form present (Al(OH)4- predominates above pH 7) . It reaches a minimum just below pH 7. At all pH values above pH 7, it rises steadily, at about 10 fold per pH unit for values above pH 7.5.

 

[Scott Campbell]

While I cannot post it here. Aquatic Chemistry concepts by Pankow shows the solubility of aluminum in fresh water as a function of pH (Figure 11.4, page 236), and shows every form present (Al(OH)4- predominates above pH 7) . It reaches a minimum just below pH 7. At all pH values above pH 7, it rises steadily, at about 10 fold per pH unit for values above pH 7.5.

That makes perfect sense. But it still appears aluminum solubility is most evident below 6 and above 8.3.

Aluminum toxicity also does not seem to be something that an organism would adapt to. Plants with a sensitivity to aluminum remain stunted as long as aluminum is present. And I would think aluminum toxicity would impact the entire tank more broadly. I would also think aluminum toxicity would become apparent more gradually. Why sponges and leathers are impacted more, quite suddenly, and often temporarily would indicate something other than aluminum toxicity to me. I would suspect ceramic dust - which could be a huge irritant for filter feeders like sponges. Much like my clams closing up when I put food in the tank, I can easily see sponges and perhaps leathers being very sensitive to the dust a Marine Pure block would kick off. Ceramic dust is impressively persistent. A soft, highly porous form like a Marine Pure block could produce a lot of ceramic dust. And the dust would cause an immediate reaction, could fade in intensity over time, could remain intense if the block is disintegrating, would primarily only impact filter feeders and would show up as aluminum in a Triton test. My spheres also seem less fragile than the blocks which may explain why I have never noticed any leather or sponge irritation.

So I still think it is more plausible that significant aluminum toxicity is only kicking in at higher pH ranges. Otherwise the impact would be considerably more noticeable to everyone using these blocks. It would probably harm most organisms in the tank, symptoms would not abate and there would be few, if any, people posting about how much they love the Marine Pure products. But ceramic micro dust can be an immediate, specific, dramatic and usually temporary irritant to a number of filter feeders.

I absolutely find it a comfort that a sensitive plant does not experience aluminum toxicity within a certain pH range despite living years in a small, cheaply made, completely ceramic container made of alumina. There may not be a hard threshold as you point out but it appears, at least for orchids, that a working threshold does exist. Saltwater may slightly alter that working threshold compared to fresh water, but I suspect pH is still the main factor.

 

[Randy Holmes-Farley]

So I still think it is more plausible that significant aluminum toxicity is only kicking in at higher pH ranges. Otherwise the impact would be considerably more noticeable to everyone using these blocks.

In my testing, you need to get to fairly high levels of dissolved aluminum to cause toxicity (e.g., leather corals closing up), and many folks have aluminum that does not rise to that concentration:

Chemistry And The Aquarium: Aluminum In The Reef Aquarium ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/issues/july2003/chem.htm

 

[Scott Campbell]

In my testing, you need to get to fairly high levels of dissolved aluminum to cause toxicity (e.g., leather corals closing up), and many folks have aluminum that does not rise to that concentration:

Chemistry And The Aquarium: Aluminum In The Reef Aquarium ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/issues/july2003/chem.htm

So that begs the question - why do folks with large blocks of alumina silicate compounds in their aquariums not have sufficiently high levels of dissolved aluminum to cause toxicity? And why would leathers recover if the source of aluminum remains in the aquarium?

 

[Randy Holmes-Farley]

My expectation is that dissolution of media such as alumina is kinetically slow and aluminum release does not reach the solubility limit. Many people report aluminum in Triton tests, but hardly any reach the 0.5 ppm level where I saw clear effects.

So I don't think it is surprising that few folks see effects if the levels attained are often not high enough to cause apparent effects.

 

[Scott Campbell]

My expectation is that dissolution of media such as alumina is kinetically slow and aluminum release does not reach the solubility limit. Many people report aluminum in Triton tests, but hardly any reach the 0.5 ppm level where I saw clear effects.

So I don't think it is surprising that few folks see effects if the levels attained are often not high enough to cause apparent effects.

Marine Pure might use that in their next marketing campaign - "Buy Marine Pure - aluminum levels not high enough to cause apparent effects!".

Thanks for the responses. Greatly appreciated! Enjoy the holiday weekend!

 

[jason2459]

My expectation is that dissolution of media such as alumina is kinetically slow and aluminum release does not reach the solubility limit. Many people report aluminum in Triton tests, but hardly any reach the 0.5 ppm level where I saw clear effects.

So I don't think it is surprising that few folks see effects if the levels attained are often not high enough to cause apparent effects.

I have hit .1ppm and my fiji leather coral did not look itself. I will be curious what my Al levels are at now and my fiji leather doing much better.

 

[Randy Holmes-Farley]

I have hit .1ppm and my fiji leather coral did not look itself. I will be curious what my Al levels are at now and my fiji leather doing much better.

Ok, thanks. My nearest data points were 0.05 ppm (seemingly OK) and 0.5 ppm (bad).