Announcement re ph, ph tests, etc. Don't


Staff member
RC Mod
...bother with ph. Ph tests are...

...fairly worthless. They're useful in freshwater. Not in salt. What you should be tracking, part of a more complex chemistry, is alkalinity.

If your magnesium level is above 1200 (1350 is a nice place to park it) and your alkalinity is around 8.3 (down to 7.9 is fine, but again, 8.3 is a good parking spot)---and your calcium is 420---EVERYBODY tends to be happy. If you have stony corals, you can feed them adequately without a doser just by dumping a fair quantity of kalk (aka pickling lime) in your topoff reservoir and whisking it around once with a stick. Period. (The ideal dose is 2 tsp per gallon, but since ro.di water can ONLY dissolve 2 tsp per gallon anyway, the residue will just lie there on the bottom until you add more fresh ro.di and stir it around once. Magic. And convenient. If you have the room for a nice reservoir, you don't need a calcium stirrer. Frankly, I've never had a stirrer worth the expense.) And as a note, a fish-only or softie tank is going to be very happy with these readings. There's just no need to keep kalk in the topoff if you don't have stony coral. Just set your calcium level with a spoonful of calcium in the sump. BUT if you do have stony coral, you DO need to go to kalk (I use Mrs Wages Pickling Lime) to save yourself the huge expense...if you spoonfed calcium to a coral reef, you'd have stack of those spendy little jars. No stony coral, a spoon or two will do. As a note: I use Kent cal, dkh buffer and Tech-M magnesium and I use Salifert tests, which return a numerical reading with precision. Other companies are good, too.

If you maintain the levels I've given above, your ph will take care of itself (it tends to fluctuate by the hour in marine tanks) and your tank can survive weeks without significant fuss or adjustment. Just test the alk weekly. If it's sinking, your magnesium has run out. Test and dose appropriately.

When you add these elements, wait 8 hours (or more) to retest between doses of dkh buffer (which corrects alk) or calcium or magnesium, because they take time to dissolve and work through the system.

This is how you DARE go on a two week vacation with your tank in the hands of your completely novice (I can't raise guppies) neighbor. If the topoff water holds out, you will come home to a happy tank. I once had to be gone 4 weeks, and just left a second Brute trashcan full of calcium-laced ro/di next to the first one with orders for my 'sitter to just switch the hose to trashcan B when trashcan A ran out of water. (I also provided plain frozen food cubes and precise orders as to how many to drop in, no more than that. Fish can live fine on a limited diet for a few weeks. Never let a tank sitter make up their own mind as to how many to feed.) The tank thrived.
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