what does "topping off with freshwater" mean? is it 1.000 salinity water? or normal WC water?

[stE25wy14]

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[BeanAnimal]

RO/DI Stewy

 

[56longroof]

Topping off refers to adding back freshwater to compensate for evaporation. The salt does not evaporate and as freshwater leaves it increases salinity.

 

[Garf]

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Pure freshwater to account for evaporative loss. Reverse Osmosis DeIonised, normally.

 

[Garf]

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You've had a tank for 9 or 10 months? Perhaps you have been doing this without understanding the terminology?

 

[EricR]

You've had a tank for 9 or 10 months? Perhaps you have been doing this without understanding the terminology?

Yeah... glancing through OP's tank thread, there's mention of 1.035 salinity,,, and invert loss.

@stE25wy14, the answer to your original question is, as other's have posted:
You need to replace water loss from evaporation with 1.000 SG (fresh) water.

If you've been topping off with saltwater, that'll just drive your tank salinity up (through the roof).
That would easily explain lots of issues.
...but, wouldn't you have noticed the salinity constantly increasing in your tank by now? (((that's the confusing part to me)))

 

[BryanM]

RODI for the win.

Though I think it is a fairly common mistake to top off with salt water, but as people pointed out, salt doesn't evaporate.

 

[KrisReef]

RODI for the win.

Though I think it is a fairly common mistake to top off with salt water, but as people pointed out, salt doesn't evaporate.

Actually, salt creeps.

So to compensate for salinity changes we test with a reliable hydrometer and then add freshwater (RODI with low or zero TDS) to replace water evaporation or add a bit of salt when salinity is low. Adding salt should be dissolved first to prevent burns to animals, but I have seen it dumped by the bag full into a sump at a wholesaler who had designed a lowflow area where the salt could dissolve to raise salinity after a days shipments had lower the system salinity with an ATO replacing salt water with fresh.

For reefer's conversations:
"Freshwater" is salt free, usually RODI water.
"Saltwater" is freshwater + salt.
"Water change" is saltwater mixed to compensate and exchange old tank water with freshly made saltwater.

 

[topjimmy]

Actually, salt creeps.

So to compensate for salinity changes we test with a reliable hydrometer and then add freshwater (RODI with low or zero TDS) to replace water evaporation or add a bit of salt when salinity is low. Adding salt should be dissolved first to prevent burns to animals, but I have seen it dumped by the bag full into a sump at a wholesaler who had designed a lowflow area where the salt could dissolve to raise salinity after a days shipments had lower the system salinity with an ATO replacing salt water with fresh.

For reefer's conversations:
"Freshwater" is salt free, usually RODI water.
"Saltwater" is freshwater + salt.
"Water change" is saltwater mixed to compensate and exchange old tank water with freshly made saltwater.

I put undissolved salt in a cup in my sump to raise it slowly if needed.

 

[Garf]

I put undissolved salt in a cup in my sump to raise it slowly if needed.

Yes, that works but why do you get in that situation?

 

[topjimmy]

It's not often, once was because my ATO was stuck on

 

[SonOfaGoat]

Yes, that works but why do you get in that situation?

I know for me I stopped WC fighting dinos. But my skimmer continued to run at times. My tanks 25g so couple skimmer cups of salt water out and ATO adding fresh - lowered my salinity from 1.026 to near 1.024.