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a couple questions...

Jan 3, 2006
ok so i finally found a dealer in colorado springs. he himself has a octo tank at home. but there were a few things he said that puzzeled me. firstly, my tank here is a 55 gallon with about 10 lbs. of live rock in it and some dead corals and rocks also there is 1 inch thick aragonite sand. it has been cycling for about one month and everything looks fine (ammonia, nitrate, and nitrite are at zero). i had the salinity at 1.028, but the dealer told me that since i'm at high altitude (about 8000 ft.) my salinity levels have to be around 1.020-1.021. that seems really low to me. he also keeps alot of water flowing in his tank with submersible powerheads. i don't remember reading much about water circulation in reference to octos. he also gets his octos from fiji and he isn't sure on the species, but he did call it a bali which i know isn't really that great. he said that it is a fairly smaller octo. max 18 inches from tenacle to tentalcle i think. can anyone help me with all this stuff? does anyone know what species he might be selling?
His salinity/altitude idea doesn't make much sense to me. The water will expand a little bit as air pressure decreases, but since this is a volumetric effect a hydrometer will still give you the right answer.

The guy seems to be reasonably knowledgeable anyway, though. The so-called "bali octopus" is what shows up on most LFS distributor's stock lists. He orders them because they're easy for him to get, unlike bimacs or briareus which take a good bit of luck and timing :smile:

isn't it true that the higher the salinity the harder to achieve water-oxygen saturation (The more salt there is in the water the less oxygen can fit into that same volume of water)?
That's true, but it isn't a big effect. That might have been what he was after: by lowering the salinity the water can have a higher DO (dissolved oxygen).

Check out this calculator:


At sea level, 36per mil, 26 degrees C, max DO ~ 6.62 mg/L
Same salinity and temp at 8000 ft, max DO ~ 4.93 mg/L

That's a big change!

Now if you stay at 8000 ft and drop the salinity to 26 per mil, you get a max DO ~ 5.21 which isn't much of a change, three tenths.
The only thing I really questions is the use of all the octo blenders...I mean powerheads. Octos need alot of flow, but as I have read for oxygen saturation and filtration - which powerheads do nothing to help. I setup my tank with high flow, but with a strong external pump, not powerheads, and a trickle filter + protein skimmer.

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