• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Biomaster 850 bubble purge


New Member
Thread starter
19 Feb 2021
West Yorkshire
I have been having issues with bubbles purging fromm my biomaster 850 thermo. I have replaced all seals and had a new head unit. I have also removed the skimmer of the intake as i thought this could be tge reason. I have also jubilee clipped every connection. It doesn't solve the issue. Oase think it could be seachem matrix being incredibly efficient and the bacteria producing bubbles in the canister? Could this be the cause or could it be the filter is pulling in the fine co2 mist. Any help is appreciated 🙏
Make a 2-3 mm hole în the prefilter head. That will prevent gas collection, by allowing it to pass through.


  • 20211220_220908.jpg
    115.7 KB · Views: 179
  • 20211220_220154.jpg
    108.8 KB · Views: 185
I have heard a couple of people recommending this technique. I will way up the pros and cons regarding the warranty. But the bubble perge is that bad might have nothing to loose. Cheers for the advice
Thanks for your reply. I have already tried the seals and hose clips. Oase seem to think it's the seachem matrix (bacteria producing oxygen) but I'm not totally convinced
I’m using matrix too (1 litre) and the filter does occasional purges but you should see how many bubbles are moving around my tank when plants are pearling. No purges outside photo period. Which suggests that the only air getting into my filter is from the water.

Will try that. I do clean the pre-filter fortnightly, however will do a clean tonight to see if it makes a difference 😉
I’m cleaning mine once a week even if it’s looking clean. My personal opinion is that if filter struggles to suck water in due to dirty pre filter, hoses or intake hose is too long or bent it creates vacuum and if seals are not tight it will suck air in. Seal grease makes seals tighter 👍
Do you realise that this voids the warranty and also needs regular maintenance to keep tiny hole clean?
Yes you are correct. The thing is that we, as you said, we have tiny bubbles in our water, which will collect in any gas trap (prefilter in this case). By let them bypass the prefilter, they will not collect in order to create the burping effect.
Regarding the hole maintenance, yes, when the hole will be clogged, the burping will come back, but will disappear again, when we will unclog the hole.