Sooo my tank smells like onions?!?!?!?

about a week ago a buddy of mine came over, and during his visit he noted that my 125g tank seems to smell like onions. i never noticed the smell myself but now its driving me crazy! am i insane.. should i even be worried.. any help or insight would be fantastic. the smell persists even after 2 large water changes 40-50%

Lol, you sure the smell is really there and not phycological?  

sure its coming from the tank. and not elsewhere in the room?

Remove your hood and lighting.  Then smell your tank. Betcha its gone.

Do you feed NLS? Could the smell be garlic and not onions? When I feed Thera-A and it's been a while since a filter cleaning, I notice my tank smells a little like garlic.

Yep food will do it. I used to feed Hikari food sticks and my water would reek. I get a bit of smell from NLS too but not offensive like the Hikari was.

Massivor Pellets gets the water stinky as well. I would check filter media, perhaps do a rince. Any food partials in media will end up stinking. Cyanobacteria has a distinctive odor, but you would be seeing visual signs of it.
Do you have "dead" spots in your tank with low to no water flow? If so food particals & other wastes can gather there and rot.

i feed NLS, i do have dead spots, but thats where i pour in my water at water changes to stir everything up and suck it all out. its always certain rocks it seems that gather the stuff. could be i just need to clean the filters, did one and not the other.. ive also tried keeping the tank open the last cpl days to see if fresh air helps. o i also just recently turned off the heater's for the summer, maybe that helped?

couldn't it just be a particular additive? a scent your guest would not be familiar with.You did mention you didn't even notice before. if I remember correctly you use stress coat yeah?  smell the bottle of that.Does it resemble the odor in question?I do use a garlic additive every couple months when I do a WC and notice the distinct aroma. If you treat your water for fungus or add something to help boost the fishes immune system it will undoubtedly have garlic as an ingredient.But you most likely knew that already.

if you use seachem prime or safe your water will smell a little funky.  smells more like sulphur than onions to me though.

You can generally use Carbon or purigen to remove smells from water as well.

I've never used Purigen, but have herd amazing things about it's ability to clean & polish the water... Easy to clean and reactivate too.

I may just use some carbon see if that does the trick. trying water changes still and they seem to help

iandraco wrote:if you use seachem prime or safe your water will smell a little funky.  smells more like sulphur than onions to me though.

actually it is sulfur that you smell when you smell onions. when your eyes burn during cutting onions its the sulfur mixing with the natural moisture in your eye,crating sulfuric acid. Thats why people cry when they cut onions.