Basic Tuning Approach

This is an Advanced Level product. Due to hundreds of different aquarium plumbing setups, pumps, sumps, ect, Synergy Reef DOES NOT Provide specific tuning assistance with this overflow. We can provide basic installation assistance, but setup and tuning to your aquarium is up to you. This can be done by anyone as long as you take the time to properly setup your system. Proper plumbing of the overflow to the sump also plays a big part in turning the overflow, not just the internal plumbing. If you are not capable of doing this, please hire a professional to do so.

The Shadow Overflow can be used on many difference sized aquariums with various flow rates. We have designed it to be a versatile overflow for many different aquariums. To be able to work with so many systems, each needs to be tuned to the specific flow of that system. This will have to be decided by you on what best fits your specific tank needs.

The overflow is designed with 1.5" Drains, but can be reduced down to 1" to fit your needs. 1.5" Drains are going to give you the full capacity of the overflow with 2500 GPH maximum flow. Reducing down to 1" will reduce the maximum flow rate to under 1500 GPH. This guide for tuning the overflow is based on 1.5" Drains. For 1" drains you will have to use your best judgment for tuning.

You will need to use a Gate Valve to properly tune the overflow. We DO NOT recommend using a ball valve. Ball valves are only used for On/Off functions and not for adjusting water flow. A gate valve will allow for the proper fine tuning of the overflow's flow to properly balance the drains.

The Key to tuning the overflow is balancing the flow between the primary and secondary drains. You do not want to use the gate valve to raise the water level in the rear box.

We suggest starting with the basic 1.5" PVC pipe lengths listed in the below in this section.

1. Figure out your flow rate that you are running. You may need to contact your pump manufacturer to determine your flow rate. It does not need to be exact, but within a few hundred GPH.

2. Once you determine your flow rate, the overflow flow has 3 flow rates we like to start with tuning to, High Flow, Low Flow and Ultra Low Flow.

   • High Flow - Any system with over 1500 GPH running thru the overflow (shorter pipes needed)

   • Low Flow - Any system with 1000 to 1500 GPH running thru the overflow

   • Ultra Low Flow - Any system with under 1000 GPH running thru the overflow

3. Once you determine your flow setting for the overflow you need to adjust your internal pipe lengths to fit your needs. The following is a good starting point for each.

   • High Flow - Emergency x 6.75”, Primary x 2.5" to 3” + U-pipe, Secondary x 4” with U-pipe

   • Low Flow - Emergency x 6.75”, Primary x 2.5" to 3.5” No U-pipe, Secondary x 5.5” to 6" No U-pipe

   • Ultra Low Flow - Emergency x 6.75”, Primary x 2.5" to 3” No U-pipe, Secondary x 5.75 to 6” No U-pipe

4. Turn on your system pump and leave the gate valve open 100%

5. Watch the flow of the drains and see what happens:

   1. You want most, if not all of the water to be flowing down the primary drain (shortest pipe) when the gate valve is 100% open (Unless you have a High Flow System).

   2. Start closing the gate valve slowly, about 1/4 turn and wait about 30 secs to 1 minute. Then continue to adjust the gate valve 1/4 turn until water just starts to barely flow into the secondary drain.

      1. Ultra Low Flow - Once water barely flows into the secondary drain pipe, Stop and wait. It takes a little bit for your system to balance. Back it off with very slow turns until the water level is exactly even with the secondary drain.

      2. Low Flow - Once water barely flows into the secondary drain pipe, Stop and wait. It takes a little bit for your system to balance.

      3. High Flow - Water will be going down the primary and also down the secondary drain. You will use the gate valve to balance the flow to quiet the system.

   3. Make sure the water in the rear box is close covering the 2 input bulkheads coming in from the aquarium. You want the water level almost above the incoming water when finished for the quietest operation.

   4. Wait. After getting it to the quietest setting, wait. The water does take time to balance and purge air. You may hear popping and bubbles. This is normal for initial setups. Allow it to sit before changing any internal pipe configurations.

After tuning, In newly setup aquariums, you may still hear slight trickle noises inside the pipes or front overflow box. This is normal. As the aquarium builds up bacterial slime with the biological cycle, it will coat the inside of the pipes and your aquarium. This bio slime will help reduce any final noises you may hear.

Other factors

Check that your external drain pipes to your sump are sloped properly. Any up sloping can cause draining issues and create less flow to be able to run thru the drains. It also can cause noise in the rear box of the overflow. Try to not run excessively long plumbing runs to your sump. Keep it as short as possible, especially with High Flow systems.

SUMP DRAIN PIPES - Inside the sump you will need the pipes to be submerged under water. The Drain pipes need small slits cut in the pipe just below the water line to allow air to escape and not cause backup air to gurgle and belch.

Proper Drain Pipe Installation

Gate Valve Installed