Water clarity using Sponge Filter

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Aquarium Advice Apprentice
Mar 19, 2023
Indianapolis, IN, USA
I'm new to sponge filters and wonder if my expectations are too high for getting clear water. I have a 10 gal tank with a small sponge filter from ACO in it. It's been set up for a couple of months now and has ~25 neos and 4 Mystery Snails in it. I also have a 125 gal and 40 breeder that have canister filters. The 2 larger tanks are crystal clear but the shrimp tank always looks hazy.

Initially I had a small piece of driftwood in it for biofilm to grow on and had a small piece of cholla wood. While I was waiting for the biofilm to grow I had a small clump of Java Moss just free floating for the shrimp to have a hidey place. Was going to glue the moss to the driftwood. The water pretty quickly turned brownish from the tannins. I don't mind the tannins coloring the water but in the last couple of weeks the water began to look hazy. I assumed it was a bacterial bloom but noticed that the Java moss was turning brown on the bottom so removed that and replaced with some Subwassertang on ledges and some Water Sprite. Also removed the driftwood.

Parameters are good. Using remineralized R/O water, parameters are pH 7.4, Nitrites 0 Nitrates 10, GH 8, KH 4. Snails have begun to lay clutches, and shrimp are having babies.

I've done 25% water changes (one with plain R/O water and one with remineralized R/O water) and the water is still hazy. I've seen videos of tanks with sponge filters that are crystal clear and it makes me wonder what am I missing? Any thoughts what is causing the haziness and or is there anything I can do to clear up the water?


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It does look rather hazy. I always found that with sponge filters, the shrimp kick up a lot of debris or ‘mulm’ in my case and the bubbles from the uplift tube tends to keep it in suspension making the tank look a little cloudy.
You'll want to make sure that you give your sponge a good squeeze or 2 every other water change to make sure it is not clogged. ( Do this in the water you removed doing the change.) It's possible that the reason your tank doesn't clear is because the water is not freely entering the sponge. That's about the only reason why a sponge filter wouldn't keep the tank clear. Your tank may be cloudy as an after effect of the wood or possibly the dying plant.
If after all that and your water does not clear, there is a product called Acurel F which is a water clarifier. It works by coagulating the suspended particles so that the filter can remove them more easily. (There may be other brands of clarifiers but I've only used Acurel F and know it's effective. (y))
Hope this helps. (y)
Update on the hazy Shrimp tank and thanks to everyone who made suggestions! Had a significant amount of mulm under the gravel and had to resort to removing all the gravel and siphoning up the detritus over the course of the past couple of weeks until the bottom was clean. Sorted the gravel and took out the larger pebbles to obtain a more even size and only put a single layer of gravel down. I have a small aqueon siphon that has a guard on it that will prevent me from siphoning up gravel and have learned how to avoid siphoning up the shrimpies (they are so dang curious and have to check it out). The sponge did not have much debris in it even given several squeezes in water from the tank. Added some Microbacter7 to the tank to give a boost to the BB after several water changes and removing some of the items that had biofilm on them. Tank clarity is much better! Pic of one of the mystery snails in the tank carting one of the shrimp around. Have seen several shrimplets.


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