Black Sand Always Looks Dirty

I have a 40 gal octagon shape fresh water aquarium. I have black sand as substrate. I vacuum tank once a week but even in between I vacuum because white deposits lay on top of sand (drives me nuts). I have 13 male guppies, 2 male platys, 4 albino corys and an algae eater housed in the tank. I feed twice a day, morning and night, a pinch of flaked and 2 shrimp disc for Cory’s. Am I feeding too much? I have another octagons tank in another room with black sand and female guppies and platys and Cory’s and algae eater but no white mess constantly on top of sand. Any ideas..l do you think boys aren’t eating as much? Thanks!

 

I have a 40 gal octagon shape fresh water aquarium. I have black sand as substrate. I vacuum tank once a week but even in between I vacuum because white deposits lay on top of sand (drives me nuts). I have 13 male guppies, 2 male platys, 4 albino corys and an algae eater housed in the tank. I feed twice a day, morning and night, a pinch of flaked and 2 shrimp disc for Cory’s. Am I feeding too much? I have another octagons tank in another room with black sand and female guppies and platys and Cory’s and algae eater but no white mess constantly on top of sand. Any ideas..l do you think boys aren’t eating as much? Thanks!

As long as you have enough plant life to consume all of your waste and excess food and/or do frequent enough water changes, you could get away with overfeeding, IF that's what it is. I've not had the experience of keeping 20 fish in one aquarium so I don't have a definitive answer for you.

Is there regular algae for the Corys and Algae eater to eat?
Are both tanks planted similarly?

 

If you observe the tank a bit, could you tell whether the white stuff is food or waste?

 

I have light sand in my tank and think the exact same thing. Its like you can see every poop.....lol I have gravel in the other tank, I think Im spoiled that you can't see it.

 

If you observe the tank a bit, could you tell whether the white stuff is food or waste?

I’m not sure

 

Looks like food to me. Like an unfinished wafer that has come apart. Is it all over the tank? Or just in that area?

My best guess is overfeeding.

 

After seeing that picture it definitely looks like a broken up wafer.

 

I’m going to feed only once a day now and see if that makes a difference. I only feed a pinch but maybe they will eat what settles on the sand between feeding. Thanks to all for your advice it is much appreciated.