Tunze 3168 filter maintenance issue

Idech · Mar 16, 2022

I don’t know what I am doing wrong, or not doing. My 75 gallons tank has been cycled since october 2021.

Last night I changed the filter floss and removed the Seachem Matrix in a bag, on the bottom of the filter, to clean It. Once before I left it without cleaning for 5-6 weeks and it got covered in green gunk that got everywhere in the tank and I didn’t want that to happen again.

I did the maintenance at night so didn’t see anything unusual. This morning I woke up to thousands of white particles swimming in the tank, with a bacterial bloom on top. The gunk from the Seachem matrix carbon is green and those particles were white. So where are they coming from ?

Here is my maintenance routine for the filter :
- change the filter floss every 5 days
- take the filter out and clean everything accessible without dismantling it every 2 months (obviously not enough)
- change the Seachem matrix every 6-8 weeks (now I’m very hesitant to use it again).

Here is what it looked like this morning. The skimmer and filter have cleaned most of it now but the bacterial bloom is still there.

My questions :
Where are those white particles coming from and what should I do to avoid them and having a bacterial bloom ?

Do I need to dismantle the filter on a regular basis ? (I’m not strong and this is very hard for me to do).

Thanks !

rvitko · Mar 16, 2022

Typically, a reef tank should have enough biological surface area without biological filter media being needed. I would doubt it is a bacteria bloom. Is the Seachem Matrix you use the biomedia or the carbon? My main thought would be that the pump is obstructed by too much media or too fine of a filtration and calcium deposits are forming on the filter and then after cleaning the precipitate blows out since the flow returns to normal. I don't think the media is the issue, I would just use less of it. The type of floss may also be a culprit, I frequently see people use non aquarium specific flosses thinking it is a savings and my experience is that it is not. Upholstery type flosses are not treated the same way, they are random instead of a combed/oriented strand, this makes them clog much faster, they also contain residual phenols which trigger bacteria blooms and cause protein skimmers to freak out and while you can do a long hot water rinse and remove most of the phenol, it just isn't as cost effective as good filter floss. Good aquarium floss can be rinsed and reused so many times that it is a hard value to beat as the combed strands don't mat up. I would probably verify that Ca, KH and Mg are all good, around 420-450, 8-10 and 1350-1400 would be my targets, I would then try packing the filter more lightly, the same medias should be fine, just less of it and more loosely installed. In general the full filter should not need to be broken down more than every 6 months to clean the pump and your maintenance sounds fine, in general though if this is Matrix carbon, my personal preference is to use less carbon and change it more often and if it is Matrix bio media, it should not really need replacement, it should just be lightly rinsed in aquarium water and reinstalled unless the media is deteriorating. I couldn't find out exactly what matrix is, usually such medias are either sintered glass, clay or ceramic or they are zeolite, zeolites can break down and make dust some super porous glass and ceramic medias can abrade and make fine dust.

Idech · Mar 16, 2022

Thank you for your detailed answer.

The Seachem Matrix is the carbon, supposed to last 2 months without needing to be replaced.

Here is the filter floss I am using now (the bag is almost empty). I just realized they call it « filter fiber ».

Here is my next bag to be used. It’s really different than the one I’m using now :

Here are my parameters as of this past Saturday. I have dosed magnesium (Brightwell magnesium-P) according to Holmes-Farley’s formula the last two weeks.

No more dosing it hopefully. The formula said to add 141g, which I did, very slowly, making sure it was needed. For the past 3-4 days I have only dosed the usual AFR (5 ml/day).

The salinity is high because I forgot to turn my ATO back on for 1-2 days.

With this additional infos, do you still believe my problem is a calcium precipitate caused by too much « filter fiber » blocking the filter ?

Also, where in the filter are those particles coming from ? The bottom part that I can’t clean without taking it apart ?

Thanks again for your time.

rvitko · Mar 17, 2022

The first floss is a type that will clump, the second one looks better but is quite dense. My preferred flosses are Eheim EhfiSynth or Tunze Fine or Course filter wadding, the course is generally ideal as it does not clump, is fairly free flowing and a deeper bed can be used without issue. I promise while these may seem expensive, if you rinse and reuse them, which you can many times, they are cheaper than all other options and it does not take much, a package of any of them should last several months. The chemistry looks good, I suspect the filter is clogging and causing some precipitation, a filter or pump removes calcium by vacuum and heat degassing the water causing a localized pH increase. Higher Mg levels do help to some extent, but nothing is really wrong with the values you have, my only caution though is comparing home test kits to ICP Mg, tends to actually be 50 or so ppm lower than a home kit result and Ca tends to be slightly higher (10-20ppm) and I would trust the ICP more. I might try using half as much carbon and changing it twice as often, this is generally a better practice only because while carbon may last longer depending on type, carbon binds substances very loosely, if something more attractive comes along, it drops what it previously trapped.