Why Can't an ATI Skim Dry

hiepatitis · #1 11/26/2007, 01:23 AM

I am curious why the ATI line of skimmers can't skim dry? Or can it?

sjm817 · #2 11/26/2007, 01:28 AM

It depends what you call dry. The rumor that they only skim a wet tea color is false. I can have my BM250 skim wetter or dryer same as any skimmer. I never set up a skimmer to run dry enough so that skimate builds up in the neck. I want it in the cup. A clean neck runs better.

This is how it typically runs:

I can also set it up for darker, AKA a dryer setting:

hiepatitis · #3 11/26/2007, 11:52 AM

I've heard from other owners of BM's that they couldn't get it to skim dry.

Wryknow · #4 11/26/2007, 12:36 PM

I think that it's very easy to get it to run dry - you just keep it in shallow water (my sump depth is about 8") and open the gate valve. It will run so dry you'll get a 1/4" slime coat on the skimmer neck in a couple of days with pitch black skimmate. If your sump level is too deep relative to the skimmer then you won't be able to get a "dry" skim because of the back pressure from the water column.

There is a certain maximum water column height on the ATI due to the joint on the collection cup and neck but this limits the ability to skim "wet," not "dry." You cannot set the internal water level higher than the joint because the water spills out (the collection cup is held on by friction only so the joint is not water tight.)

africangrey · #5 11/26/2007, 01:10 PM

I own a BM200, and have it sitted at 6 1/2" deep in the sump. An little Deltech style air valve was introduced by a local dealer of mine in the Bay Area to control the amount of the air drawn by the Secci pump.

I was constantly adjusting the gate valve for lowering the bubble break level to get it a dryer foam. Over time the foam level would rised to generate light tea color until I discovered that the little air valve has been quickly accumulated with salt creep, and needs to been clean with squire of fresh water daily to clean out the debrise.

In my opinion this skimmer can skim dry but you will have to monitor and inspect it daily to make sure the air valve is nice and clean. By the way, I removed the air silencer to get a better view of the valve, just have to get use to the loud noise coming from the air drawn.

I am sure there is a better way of prevent the salt creep, may be by routing the air tube away from the aquarium.

koraltek · #6 11/26/2007, 01:35 PM

what you should do is get an extention hose for the top of the air valve, and make it go through the hole in the top of the muffler, then you can just put the end of the hose in a cup of hot ro water without having to disassemble the air line each time for cleaning.

and yes, you can make the bm's skim dry

King-Kong · #7 11/26/2007, 02:38 PM

I have a 250 and can easily set it to skim dry.. I have the outlet closed off quite a bit, so openning it up a bit (love the valve they use.. can easily fine tune and keep hands dry) will cause much much drier skimmate.

Maximus · #8 11/26/2007, 02:45 PM

This is partially my fault. I had the 1st BM250 and it was hard for it to skim dry. I had one of the original models and didn't have an air valve or other devices on it. It looks like the newer models are now improved and come with gate valves and air valves.

sjm817 · #9 11/26/2007, 02:54 PM

Mine has no air valve, and is the style with the standard outflow with the wingnut height adjustment. Its bone stock. AFAIK, they still dont come with airvalves. People add them on.

CruzinKim · #10 11/26/2007, 03:56 PM

In earlier threads, I've read that the earlier versions of the BM200 and BM250 (version 1 and 2) had a center neck riser tube and the exhaust riser tube that was too small in diameter. Also, the mesh diameter was too large and no control over the exhaust. It sounds like a combination of all the above forced the skimmer foaming to be really high in the neck and could not be adjust lower, so it skimmed too wet and could not get dry at all. Even if the sump water level was down to 5" to 6" low, one couldn't get dry skimming.

That's all change with the later versions 3 and 4 and no longer an issue. Sometimes it just pays to wait at least 5 months for a new product to work out all the fine tunning needed to get the unit to work at its best. Especially from overseas, so much to consider besides just the voltage difference.