Basket floating on aquaclear 70

[GJerry]

On one of my tanks I have an AC 70. The basket keeps floating on me. I squeezed out the sponge and cleaned the filter really good. Put it all back together and 12 hours later it was living again. I then bought a new sponge rinsed it put it in and 12 hours later is pushing up again. The sponge starts to bow in the middle and eventually lifts the basket.  It is happening with a thoroughly cleaned filter and a new sponge with a decent amount of Seachem matrix on top. I had the filter running since last august and never had an issue until about a week ago. Any clues on what the problem is? It can’t be a clogged sponge since the sponge is new. 

[GJerry]

Here is a picture of a new sponge being forced up. This was after 12 hours.  

[kimberbee]

Is it installed correctly? Aren't there little groves the basket fits in? Pretty sure there are on the ac20... 

[GJerry]

Yeah the grooves are only on the side that doesn’t float up. It is down and the hooks are in the right side of the basket. That is why only one side is floating. I am wondering if air is trapped in the sponge and being lifted gradually. I am truly at a loss. Filter has been fine since august and now it is doing this weird stuff

[kimberbee]

Sorry, no other ideas here... 

[DSA65PRO]

I had a similar problem with media floating and turning sideways. I purchased some large flat “Marbles,” from a craft store, problem solved. 

[GJerry]

I just checked again and it was lifted. Took about 4 hours. I don’t get why it just randomly started. Thinkin about adding a hook on top to keep the basket from lifting on that side or just getting a different sponge and stop using fluval sponges. I am really at a loss on what is going on. 

[GJerry]

So I have been watching it. It is 100 percent cause by the sponge. The first couple hours the sponge stays down. Then it starts to bow in the middle as the middle portion that is not held down by the tabs starts to rise it forces the basket up. I have tried three sponges. They all do it. 

[GJerry]

A small update in this filter. I think the reason it is floating up is because it is trapping air in the sponge. I can see bubbles under the sponge. I don’t know how this happening the sponge has been sufficiently soaked to the point where it sinks in a bucket of water. Somehow air bubbles are building under the sponge and cause it to rise. 

[Ratvan]

Why are you running the sponge out of interest?

[GJerry]

Just to help pull out crap that is sucked in. Basically as a mechanical filtration for larger particles (food, waste, etc.). I called Haram and they are sending a new basket and sealed if it doesn’t fix it I could send in the filter for replacement. I am thinking about removing the sponge and just fitting a generic pad I there for particle removal and then just adding more Seachem matrix. 

[Ratvan]

20 minutes ago, GJerry said:

Just to help pull out crap that is sucked in. Basically as a mechanical filtration for larger particles (food, waste, etc.). I called Haram and they are sending a new basket and sealed if it doesn’t fix it I could send in the filter for replacement. I am thinking about removing the sponge and just fitting a generic pad I there for particle removal and then just adding more Seachem matrix. 

Was going to say why not run a filter pad or floss for detritus

[rcbirbman]

Same things happens to me - going to try and weigh it down with flat stones as others suggested. Sponge is definitely the source of the issue. It floats and pushes the other filter material up, causes the basket to shift, and pushes the lid up. 

[Lily1]

I have the same floating sponge problem is in all my AC 70s & the AC 60-110.s.  Got great idea here.  Will replace their sponge with some pricey black aquarium sponge sheets bought for my sump filter.  How can a big company make such a flawed design?  This has been driving me nuts. 
 

EDIT: Decided against replacing foam.  Nice bacteria live there. Used pebbles to weight down basket.  Some limited success.  Moved aerator as far from filter as possibly, seeing if that helps.