Water movement and clam


New member
After patiently waiting (13 months) and reading a lot on reef central (thanks) I finally bought a 3” Deresa this weekend. The tank was ready and I had saved a perfect spot for it. Now I’m afraid the water current is too much. Everything talks about low to moderate current, but how do you know? I noticed the clam mantel moves slightly from the current. Is this to much?

The clam seems happy. Good mantel extension, very responsive to light changes, but it new to me.

Another simple question
Do clams close completely at night or do they stay slightly open?
Also how do you know when a clam is not happy. I’ve read about the big things but what about the small signs I should look out for?


In Memoriam
kudos to you on waiting and researching, not many people do that.

If the clams mantle is constantly folded over in an unnatural postion then you should worry. Moveing gently in the current isn't a problem and it sounds like your clam is ok.

Clams stay slightly opened. When a clam closes up completely it is putting a great deal of strain on its muscles. This is actually a bad thing if it stays closed for a pieriod of time.

If your clam isn't developing white spots and bleaching that means it is getting enough light. If you can visually see new white shell growth under the mantle it is doing good at growing.
If the clam keeps moveing or tipping over on it's side it isn't happy with it's location. You should try a different spot.

Other than that it sounds like you are on your way.


New member
Great thanks for the info... Like I said in my mind it is a perfect spot. I'll be keeping an eye on it every day. Whenever I figure out how to take a good picture of my tank I'll post a pitcure.

Diana Caye

New member
Just today I was reading through Eric Borneman’s ‘Aquarium Corals’. He gave these specs on page 336:

Low Flow: 0.5 â€"œ 2 in/sec
Medium Flow: 2.5 â€"œ 8 in/sec
High Flow: 8 â€"œ20 in/sec
Very High Flow: >20in/sec

He said to get a yardstick, a watch with second hands, and some food. Then place the ruler anywhere on the tank and drop in the food. He uses a single adult brine shrimp. The number of seconds it takes for it to travel a certain distance is an approximation of the flow rate.