Vacation plans for reef setup

[idoc]

I am leaving for five days' vacation. I have calculated that in that span, my tank will require approx 2-3 gallons of extra water to offset evaporative loss so my sump filter and power head will continue to function normally. Can I add the extra water to my sump without destroying the fauna residing on the bioballs?

[Ninong]

I don't understand your question. You cannot add freshwater now to make up for evaporation that has not yet happened. And any water added to your sump now, whether it is saltwater or freshwater, will not change the fact that your tank will still lose water by evaporation during the next five days.

If your system (tank and sump together) is capable of operating for five days without any water being added, then you're good to go, assuming nothing else goes wrong. The only thing you can do now is to make sure that your water level in your sump is as high as you can take it and have the equipment still function properly. In other words, you have an optimum running level in the sump but you have leeway above and below that level. Your optimum operating level might be 6" but you might still be able to operate the system with a level of 7", but if it drops below 3", your pumps may start pulling air.

Just for the purposes of example, we will assume that you can run as high as 7" and as low as 3.5". That's a net range of 3.5". If your sump measures 24" x 12", then that 3.5" equals 4.36 gallons, minus volume taken up by any baffles or equipment. Let's call it a net of 3.5 gallons.

You can easily calculate how much capacity you have in your sump. Just take the highest level you can run your sump and still allow enough capacity to accomodate a power outage, assuming your equipment (skimmer, etc.) will still operate satisfactorily at that level. Then take the lowest level that your sump can operate and still have all of the equipment operate satisfactorily -- that means the skimmer and all pumps. Subtract the lower figure from the higher figure. Now take the length of the sump in inches times the width of the sump in inches times the net difference between the upper and lower levels and divide the result by 231 to get the gross volume in gallons. Now estimate the volume taken up with the thicknessof the sump's walls, thickness of the baffles and any equipment in the sump and subtract that.

You should already know your sump's optimum operating level and I assume that you have, on occasion, run it slightly higher than that level because you didn't want to be bothered adding water the next day or two. I dripped limewater (Kalkwasser) into my sump every night for evaporation replacement but I knew that I could skip two days if I was going away for the weekend by simply bringing the water level in the sump up to about an inch higher than the normal operating level first. After two days of not adding any water (meaning limewater), my sump's water level would be down to about 2" below it's normal operating level -- a net change of 3". Each inch change in my sump represented about one gallon. I could not skip more than two days in a row without my pumps starting to draw air. In practice, I never skipped more than one day without adding water (limewater). If I went on vacation for more than 48 hours, I had someone else add water to the sump in my absence. I didn't trust them to drip limewater, so I just had some R.O./D.I. water available for them to add to the sump each morning to bring the level back up to the mark on the outside of the sump.

There were two reasons why I couldn't run my system more than 1" above the optimum operating level: 1) The skimmer would not function properly, and 2) Running at the optimum operating level meant that if I turned the power off (to feed, for instance), the water level in the sump rose to within 2" of the top of the sump. Therefore, if I increased the operating level more than 1" above the optimum level (as marked on the outside of the sump), the sump might come very close to overflowing in the event of a power outage.

Not all skimmers are the same. Each has a different acceptable operating range when it comes to the depth of the water in the sump. You have to determine that for yourself by experimentation. My skimmer was external but it had only about a 3.5" acceptable operating range. My system return pump and my skimmer pump were both external but the system return pump would start freaking out if the water level in the sump fell to within about an inch above the intake. What it all came down to was that I could run my sump as high as 7" or as low as 3.5" and that was it. The normal operating level was 6".

The ideal situation would be to have an automated top-off system so that you didn't have to worry about such things. You would just have to worry about the auto top-off system working properly while you were gone.

[Ninong]

Why do you have bioballs in your sump???

If you have live rock in your aquarium, you don't need bioballs in your sump. If you have live rock, a sand bed and a protein skimmer, you really don't need bioballs in your sump.