New airpump might contain silica gel

Queequeg · Mar 21, 2014

Just bought an aquarium airpump for aerating my wort. The thing does 500L/m up to 16PSI so should aerate pretty fast with a 2um stone up to 8ppm. My plan is to also put a T connector pre filter in the line and connect it to a disposable oxygen canister to boast high gravity beers to above 10ppm.

Anyway the air comming from the pump has a distinct and fairly strong smell of silica gel. Do you think this would have any spoiling impact on my wort.

I plan to run the pump for several days to see if the odour dimishes, if could just be that the parts were just stored in silica. Other options consist of aerating a commerical beer and trying it straight away (of course this dosn't account for off flavours that can form with time) or opening up the pump and removing any silica gel that might be present.

According to wiki silica gel is pretty unreactive and can actually be used in food. Still I'm more worried about taste than toxicity.

EDIT: I have just read that silia gel is odorless, that news to me. So perhapes its something else. It smells sort of rubbery/medicinal.

broadbill · Mar 21, 2014

Queequeg said:
Just bought an aquarium airpump for aerating my wort. The thing does 500L/m up to 16PSI so should aerate pretty fast with a 2um stone up to 8ppm. My plan is to also put a T connector pre filter in the line and connect it to a disposable oxygen canister to boast high gravity beers to above 10ppm.

Anyway the air comming from the pump has a distinct and fairly strong smell of silica gel. Do you think this would have any spoiling impact on my wort.

I plan to run the pump for several days to see if the odour dimishes, if could just be that the parts were just stored in silica. Other options consist of aerating a commerical beer and trying it straight away (of course this dosn't account for off flavours that can form with time) or opening up the pump and removing any silica gel that might be present.

According to wiki silica gel is pretty unreactive and can actually be used in food. Still I'm more worried about taste than toxicity.

EDIT: I have just read that silia gel is odorless, that news to me. So perhapes its something else. It smells sort of rubbery/medicinal.

not sure about the smell (other than the fact that its an aquarium pump so I don't know if it was designed to produce clean-smelling air necessarily)..

About connecting this oxygen tank....you are going to need a regulator to lower the flow/pressure (i.e. you can't just hook up the tank and oxygenate at full blast). My question is; if you have the diffusion stone, and the regulator, and the tank....why bother with the aquarium pump in the first place?

Queequeg · Mar 21, 2014

I think its the smell of the diaphragm as diaphragm are commonly made of rubber and that is the smell.

The oxygen can is an aerosol (sold for athletes) and not a tank, consequently you can't fit a regularly and the pressure drops with use, hence the pump system. This works out cheaper than me getting an O2 tank and reg. In the UK laws are tight on the sale of O2. This is the best solution I could come up with as it uses only a few seconds to pump up the O2 and I should get many batches from a single 15L aerosol O2 can.

Its definitely the diaphragm, as the spare part is rubber. Looking are replacements for different pumps they all seem to be rubber. I googled "teflon air pump diaphragm" only to get pumps in the region of £300. So I guess the pumps sold as homebrew ones still use a rubber diaphragm.

Does anybody have experience with this?

Edit: looking around this seems a fairly common observation even in pumps sold for homebrew use. Some claims a filter takes care of the issue. I have some 0.22um that I plan on using. I also have some activate carbon that I could put in the 9mm tubing leading to the stone.

broadbill · Mar 21, 2014

Queequeg said:
I think its the smell of the diaphragm as diaphragm are commonly made of rubber and that is the smell.

The oxygen can is an aerosol and not a tank, consequently you can't fit a regularly and the pressure drops with use, hence the pump system.

You do realize that if it is an aerosol that it would have propellants in it? It could be something benign like CO2 or nitrous oxide, but there are some nasty ones you wouldn't want in your wort.