My water is getting a bit of cloudy lately and I dont know what caused it.

All possibilities of causing cloudy water that I can think of are:

1) New Tank Syndrom (Not applicable in my tank)

2)Bioload (I tested water, there is no Ammonia present and all other parameters are normal)

3)Overstock (I have three 5" in a 30g and do 80-90% w/c twice a week, so I dont think this will be a problem and causing cloudy water)

Are there any possibilities that might cause the cloudy water? I have been leaving the light OFF for the past 4 days due to the heat wave in Northeast coast. The water temp is around 82F without the light on. Also I have a bag of activated carbon which it has been in the filter for couple weeks now. I'm not sure the old cabon will causing the cloudy water. I think the activated carbon has a life span of 3 weeks?

Bacterial bloom of some sort?

Fish diarrhea?

Try putting some of the water in a white mug to see if it is white, green, brown, etc. Sometimes you can see colors in a white mug that are not apparent in the tank and that will help you to determine the cause.

I should of post this before the w/c. I just did a 90% w/c, so I have to wait to test the water in a white mug.

Thanks for the tip.

Have you had any spawning behavior lately? A spawn can foul a tank in a matter of hours and make the water cloudy. Perhaps lookout for that.

There are also water-born algae that just float around in a tank (e.g., green water) that can cloud things up.

Carbon can fill up in a matter of days ...I only use it to remove meds ...are you feeding different foods???

My fish stopped the chasing, so I dont think spawning activities is ongoing at this point.

I used cabon to remove the Prazi before n I was too lazy to remove it. Anyway I removed it yesterday.

I have been feeding different types of food such as frozen mysis, bloodworms, brineshrimps, dry food such as pro-gold and other one that I used to feed to my cichclid fish. I just dump it in the tank whatever I can find in my drawer.

I would just cut bsck on the feeding and see what happens ....

I have found that freeze-dried bloodworms have powder in them and if you feed a lot they cloud the water...

How many gph are you turning? What is the medium used for mechanical filtration in your tank?

I am assuming this 30 gallon tank is standard rectangular design....

I feed frozen bloodworms, not the dry one.

I have two OH filters total of 500GPH turning rate. I cut the whisper carbon bag into small pieces and jam them in both filter. The AC 70 seems very powerful, but the Whisper 4 seems produce less turn over rate after I added the filter media as well as a bag of bio-balls.

I just got myself a band new 38G tank, hopefully these two filters can keep up with a bigger tank.

Note: You say your tank has 0 ammonia, but after the bacterial bloom its too late to test for it. Most times a bacterial bloom are cause by a spike of nitrates + ammonia, so after the water is cloudy the bacteria have already fed on it. POSSIBLE CAUSES:
1)Overfeeding
2)Stirring up substrate
3) imbalance of nutrients ( too much poop/ nitrates?)
If you stirred up your gravel to plant something or maybe just to move it or an ornament around, this often causes bacterial blooms. Waterchanges should always be done after doing this.

I have a BB tank, and highest nitrate level registered was at 15 PPM. I do massive w/c twice a week. So overfeeding might not pose a big problem. I'm confused.

Is the water cloudy coming out of your tap?