Skimmer Effluent Smell

5Bucks · Jan 28, 2015

From what I've read many experienced reef keepers don't bother to test po4 levels. They let things like algae growth guide their determination of nutrient levels. Anyone else smell their skimmer effluent and use it as a gauge for nutrient levels? I've had a few bounces recently. Went from po4 of .23 to Hanna .00. Then upped feeding a bunch in hopes of adjusting to to something around .03. Over did the feeding and bounced back to .09. One thing I noticed is, and maybe it's just coincidence is the change in smell of what drains out of the skimmer. When po4 is high the smell is awful...like gag worthy. When near .00 I could stick my nose in the collection jug all day and it almost smells sweet! Thankfully, with new GFO, reduced feeding and water change I'm back to skim that smells sweet!

Randy Holmes-Farley · Jan 29, 2015

Interesting. I've not heard of anyone notice that before.

I think in part skimmer smell relates to the organisms in the tank by what types of organic matter they produce.

My skimmate has never had a bad smell. It always smells "oceany".

redfishbluefish · Jan 29, 2015

I use a skimmate container and collect mine. I can tell you that it has never smelt sweet. It always has a sulfur smell (rotten eggs). I'm wondering if the ratio of sulfur to phosphate would actually answer that question of sweetness. That is, assuming a ratio of sulfur to phosphate (sort of like the Redfield Ratio for C, N and P), when phosphate is reduced, so is sulfur, and therefore you have some sweet smelling skimmate.

I'm also in agreement with Randy. I can tell you when I started biopellets my skimmate changed. The bubbles remain formed into the cup and deposit on the outer part of the cup like blotches. I'm assuming all the dead bacteria from the biopellets.

5Bucks · Jan 29, 2015

I collect mine too. Perhaps "sweet" smelling is not quite correct. Should have said not offensive or doesn't make me gag - so zero rotten egg smell. Mine lost the nasty smell about 6 weeks into carbon dosing. I had also upped the flow through GFO reactor at the time. Po4 test at LFS read .00 at the time. Started feeding more, reduced GFO flow and cut back carbon dosing by about 10% and it started smelling nasty again. I'm having a tough time getting a good balance between nutrient import and export. I'm thinking relative smell of skimmate along with frequency of glass cleanings is another way of appraising nutrient levels.