Overflow, ATS and ATO

[USPC45]

Greetings,

After extensive research, I plan on building an ATS. I've been in and out of the hobby since the early 90's and I am now back "in". I'm building the tank for my 2 year old son. At each "out", I gave up because of nuisance algae. My tanks developed undesirable growth like Lady Gaga's nether regions :-P. I've tried just about everything; skimmers, chemicals, chaeto, voodoo, and whatever snake oil came along at the time. I've since amassed a collection of pumps and other equipment.
Anyway, for those that have plumbed their overflow directly to the ATS have you experienced a decrease in flow as the algae grows and restricts the drain slot? Correct me if I am wrong, but wouldn't a decrease in flow affect the water level in the sump, thus affecting the set point of the ATO? Or is this a non-issue as the screen is cleaned weekly.
I'm trying to keep the tank as simple as possible with as little equipment as possible. An ATS seems like a simple and logical solution. Thanks.

[kotlec]

I thing this is return pump that determines flow and not the drain. Your drain at all times must be designed with good reserve. For safety reasons your design must include emergency outage above ATS.

[Ace25]

I just made sure to have an emergency outlet in case the screen was blocking too much flow. The ATS pipe is the same as my overflow, 1-1/2", then I went from that size down to 3/4" with a reducer. This makes a nice lip in the pipe so water can build up and still get down the screen. If the screen clogs too much it will go over the lip and out the drain. If I slack off and don't clean for over 10 days I can hear the emergency output gurgling, letting me know the screen is full. I haven't noticed much difference in overflow/ATO though, I suspect at most it may be 1/2G difference between when the screen is full vs clean, which isn't a big enough difference to cause me any worries with salinity.

http://farm6.staticflickr.com/5145/5638737141_a2826da600.jpg

[USPC45]

Thanks for the replies!
Ace, So it looks like your reducer is at the end. During unimpeded flow, I'm assuming that no water exits through the reducer and all flow passes over the screen. BTW, I like your design nice and simple.

[Ace25]

Yup, during normal operation there is no water that makes it over the lip and out the emergency pipe. The reducer is inserted into the coupler at the end of the screen (right side of the pipe) and then goes into a 3/4" bulkhead. The valve in the picture on the emergency pipe is just used as a coupler, it isn't closed at all and I have found no reason a valve would be needed.