Aquarium Myths and Misinformation

[Jay Hemdal]

That’s a good point, but I’d have to see if that just pertains to the inside surface of the vessel, or also to the surfaces of the rock, etc. in the tank. Decades ago, I ran some tests to measure the amount of water trapped between the interstices of aquarium substrate (for more accurate tank volume calculations). I used different sized gravel in a graduate cylinder, then measured the water it took to fill the cylinder. I was surprised to see that the water volume trapped in the interstices was about 30% of the gravel volume, and it didn’t vary much with grain size until you got really far apart, like sand versus pebbles.

Surface area for biological processes isn’t much of a limiting factor in aquariums as they are normally run.

I was giving this some more thought. I can't readily think in metric, so I made a real world scenario using English units -

Two aquariums;

one is 20" x 10" tall x 10" wide. That holds around 8.65 US gallons. The inside glass area is 800 square inches. That gives a ratio of 0.011 gallons per square inch of glass area, or 92 square inches of glass per gallon of volume..

The next tank is 48" long by 20" tall by 12" wide. It holds 49.9 US gallons of water. The area of the glass is 2976 square inches. That gives a ratio of 0.0168 gallons per square inch of glass area, or 59.6 square inches of glass per gallon of water - so actually in the other direction of how I understood your comment - there is MORE water volume per wetted surface in a larger tank than a smaller one.

 

[rtparty]

Ive never had difficulty maintaining nano tanks without doing anything special whatsoever...If smaller tanks are more difficult then a large tank must be beyond easy...

My 24s, 38, 40B's, 50 cube, and many other small tanks were WAY easier to maintain than my 250g tank in most cases. Simple tasks like cleaning pumps, cleaning glass, water changes, making 2 part, etc take exponentially more time and work on a larger system IME. A 10% water change on a 24g is 2 - 5g buckets and 10 minutes. A 10% water change on a 250 is multiple Brute cans, a couple pumps, and 30 minutes at least. Those Brute cans take up more space. You have to make and store more water so now that needs even more space. I had my manual water changes pretty dialed in on my 250g but it took more time and space than 2 buckets

 

[Hans-Werner]

there is MORE water volume per wetted surface in a larger tank than a smaller one.

Yes, I have to say I have expressed it a bit too complicated and too mathematical but this is in agreement with what I said. Smaller tanks have more surfaces per volume than larger tanks which is making smaller tanks less stable.

It gets quite clear when you go to a public aquarium and look at the huge masses of water, of "empty" or "negative" space where not much happens, no coral that might consume calcium, alkalinity, micro and macro nutrients etc.. If you compare this to a crowded home tank it is easy to imagine that you have to take much more care for calcium, alkalinity, trace elements etc. in the smaller home tank.

But this "stability" of larger tanks goes in both directions. If you have something going wrong, it is much, much more difficult and costly to correct it. In a nano tank it is easy and quite cheap to do a 50 % water change. The ease of care for a smaller tank and the fact that developments go much faster and can be seen and diagnosed more easily may make it more stable in practical terms.

 

[Randy Holmes-Farley]

But this "stability" of larger tanks goes in both directions. If you have something going wrong, it is much, much more difficult and costly to correct it. In a nano tank it is easy and quite cheap to do a 50 % water change. The ease of care for a smaller tank and the fact that developments go much faster and can be seen and diagnosed more easily may make it more stable in practical terms.

Think Titanic spotting an iceberg dead ahead. lol

 

[formallydehyde]

Sorry if this has been stated previously somewhere in the thread but I just found out something I thought was interesting.

This isn't so much of a "myth" as it just is way outdated information that still gets passed around: I've sometimes seen people say you cannot use GE hardware store silicone in an aquarium because it contains arsenic, or in some versions, it's only the white silicone that has arsenic. Currently GE #1 white tub and tile silicone and white all purpose silicone do not contain any arsenic.

If you look at the material safety data sheet, they had to list titanium dioxide (titanium white) and silicon dioxide as potentially hazardous ingredients (which are both harmless unless you work in a factory where those are being blown into your lungs as powders 40 hours a week for decades) but no arsenic is listed. If they had to list titanium white they DEFINITELY would have to list arsenic on the MSDS.

However, at one point GE white silicone DID contain arsenic and they explicitly recommended against using it in fish tanks because of this. A family in the 1970s might have gotten arsenic poisoning because they used GE white bathtub caulk in their dishwasher.
Source: https://www.nytimes.com/1976/12/30/...calls-sealant-a-health-peril-but-ge-says.html
I don't know when they removed it from their silicone products but I'm betting it was a long time ago.

[The real reason not to use hardware store silicone in fish tanks nowadays is because they're potentially not strong enough for aquarium use and/or the "neutral cure" (the ones that don't offgas vinegar) versions might leech solvent into the water over time.
Also I am speaking from a US perspective so I have no idea what other countries may or may not allow.]

 

[Jay Hemdal]

Sorry if this has been stated previously somewhere in the thread but I just found out something I thought was interesting.

This isn't so much of a "myth" as it just is way outdated information that still gets passed around: I've sometimes seen people say you cannot use GE hardware store silicone in an aquarium because it contains arsenic, or in some versions, it's only the white silicone that has arsenic. Currently GE #1 white tub and tile silicone and white all purpose silicone do not contain any arsenic.

If you look at the material safety data sheet, they had to list titanium dioxide (titanium white) and silicon dioxide as potentially hazardous ingredients (which are both harmless unless you work in a factory where those are being blown into your lungs as powders 40 hours a week for decades) but no arsenic is listed. If they had to list titanium white they DEFINITELY would have to list arsenic on the MSDS.

However, at one point GE white silicone DID contain arsenic and they explicitly recommended against using it in fish tanks because of this. A family in the 1970s might have gotten arsenic poisoning because they used GE white bathtub caulk in their dishwasher.
Source: https://www.nytimes.com/1976/12/30/...calls-sealant-a-health-peril-but-ge-says.html
I don't know when they removed it from their silicone products but I'm betting it was a long time ago.

[The real reason not to use hardware store silicone in fish tanks nowadays is because they're potentially not strong enough for aquarium use and/or the "neutral cure" (the ones that don't offgas vinegar) versions might leech solvent into the water over time.
Also I am speaking from a US perspective so I have no idea what other countries may or may not allow.]

Silicone has long been a problem for me - I don't know enough about the "mildew-proof" products to say if they are safe or not, but the strength issue is a big one for me - it is so difficult to tell if a particular product is suited for aquariums or not. I now ONLY use silicone that is either labelled for aquariums, or says, "for marine use below the waterline". I use a lot of Dow 795 in instances where clear color doesn't matter.