Setup path, stage 3
Place and leak test a reef tank before adding salt
A leak found with fresh water in an empty tank costs a towel. The same leak found with rock, sand and fish costs a weekend. Level the stand, run it with fresh water and test the failure cases on purpose.
Last checked . How we check
What do you need for this stage?
- A spirit level
- Fresh tap water (it is drained afterwards)
- Kitchen roll or newspaper under the stand
- A marker pen for the sump
- An RCD plug or an RCD-protected circuit
How do I level the stand?
Check level in both directions on the stand top before the tank goes on. Shim under the stand, never under the tank. Rimless tanks often come with a foam or rubber mat; use the one the maker supplies and no other.
How should the electrics be set up?
- Every aquarium plug on an RCD, and test the RCD with its button.
- A drip loop on every cable, so water running down the cable drips off before the socket.
- Sockets and extension blocks above floor level and away from the sump.
- Label each plug so a sitter can turn off the right one in a hurry.
How do I test the sump will not overflow?
When the return pump stops, water in the display above the overflow and in the return pipe drains into the sump. The sump must hold it. Run the tank, mark the sump level, switch off the return pump, wait until the drain stops, and mark again. The space between the marks must fit with room to spare, and the running level must leave that space empty.
Then switch the pump back on and check the return does not keep siphoning when it stops (a small hole drilled in the return outlet just below the surface is the usual siphon break).
How big can the top-off reservoir safely be?
If the whole reservoir emptied into the tank at once, salinity would drop. To stay above 32 ppt from 35 ppt, the reservoir should hold no more than about 9% of the net water volume (our arithmetic: 35 divided by 32, minus one; try the ATO reservoir calculator). BRS keeps most reservoirs at or under about 10 US gallons (38 litres) whatever the tank size. Test the backup sensor by lifting the main float by hand and checking the pump stops.
What are the steps, in order?
- Level the stand in both directions.
- Place the tank and any mat, check level again.
- Fill with fresh water and run every pump.
- Leave it running 24 to 48 hours with paper under the joints and stand.
- Do the sump back-siphon test and mark the safe running level.
- Test the ATO and its backup sensor.
- Drain completely and dry before adding rock, sand or salt water.
Your checklist
Tick items as you go. Ticks are saved in this browser only and fill the depth gauge.
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What test must pass before moving on?
Before you add rock, sand or salt:
- Dry paper under every joint after 24 to 48 hours of running.
- Sump holds the full back-siphon with room to spare.
- ATO stops when the backup sensor is lifted.
- RCD trips on its test button.
What are the common mistakes?
- Shimming under the tank rather than the stand.
- Skipping the leak test because the tank is new.
- Setting the sump running level by eye, then flooding the floor in the first power cut.
- A reservoir big enough to drop salinity by several ppt if the ATO sticks.
- Leaving tap water in the tank and adding salt to it.
Where do sources disagree?
| Topic | What sources say | Our reading |
|---|---|---|
| Fresh or salt water for the leak test |
| Use tap water and drain it. Tap water left in the tank brings phosphate, silicate and chloramine into the new system. |
| How long to leak test |
| 24 to 48 hours finds seam leaks; run longer if you are still tuning a sump. |
Sources
Figures from sources read as a search summary only are shown as typical figures: check them before you rely on them. Found a mistake? Tell us how to fix it.