Lime Scale Buildup in Pump ?

[DiverDude]

Anyone else having issues with lime scale buildup in their pumps ?

The MaxiJet 1200 in my HOB skimmer seized again last night (this is with a new impeller) for the second time in 2 months.

Scrape or dissolve the buildup and she runs great for another month. This is a new issue. Water chemistry numbers are mostly where they should be (a little low on Mg (~1100) and pH is at 8.1. Water is all RO/DI and I'm using Reef Crystals (1.026).

[StirCrazy]

where is the pump? are you dosing and are you dosing close to the pump, and how are you dosing.

if you are dosing once a day in the sump and you pump is in the sump you are going to create a enviorment where persipatation of the ca is possible and the pump is a great place for it to happen, this can be compounded by a low Mg.

Steve

[DiverDude]

pump is on HOB skimmer in HOB sump. All dosing is done in a bowl of water and added directly to the display.

[whatcaneyedo]

Raise your magnesium like Stircrazy recommends.

"The extent to which magnesium gets onto calcium carbonate surfaces depends strongly on the amount of magnesium in solution. The more there is, the more it gets onto the surfaces. If magnesium is lower than normal, then it may not adequately get onto growing calcium carbonate surfaces, allowing the deposition of calcium carbonate to proceed faster than it otherwise would, potentially leading to increased abiotic precipitation of calcium carbonate from seawater onto objects such as heaters and pumps. Often the inability to maintain adequate calcium and alkalinity despite extensive supplementation, and the precipitation of significant amounts of calcium carbonate on heaters and pumps, are signs that the water has inadequate magnesium."

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH
http://reefkeeping.com/issues/2006-06/rhf/index.php

[DiverDude]

ok so I finally had time this morning to do a full load of water tests:

pH: 8.1
NO3: 0
NO4: 0
Ca: 450
Mg: 1050
Alk: 2 meq/l

So, as always, my Mg is low as is Alk. Notice how Ca is a little high.

Ok, so here is the odd bit: I've been supplementing Mg like crazy and Alk as well but no Ca. So I can't get Alk and Mg high enough but Ca is high even with no supplementation.

Tank has good SPS growth but I have a bad HA problem that is ongoing....

Doesn't seem to add up as I *should* be having trouble maintaining Ca, but I don't.

[Coleus]

I think you should dose MG to bring it up to 1350 and then try to adjust alk and calc? Do you have mangroves in your tank?

Also try different test kit to make sure