Large water change process

[Auburn866]

Ok guys I have a noob question. I'm running Chemiclean and plan on doing the recommended 20% water change afterwards. Currently I mix my saltwater in 5 gallon hedpaks which handles my bi-weekly 10% water changes. Is it ok to do a 5 gallon water change, then mix another 5 gallons and do another water change a couple of hours later or do I need to do it all at once?

 

[Azedenkae]

Ok guys I have a noob question. I'm running Chemiclean and plan on doing the recommended 20% water change afterwards. Currently I mix my saltwater in 5 gallon hedpaks which handles my bi-weekly 10% water changes. Is it ok to do a 5 gallon water change, then mix another 5 gallons and do another water change a couple of hours later or do I need to do it all at once?

In this case, either/or is fine. Doing two 10% water changes essentially consecutively is only equal to a 19% water change. But that's close enough.

 

[Patman]

Ok guys I have a noob question. I'm running Chemiclean and plan on doing the recommended 20% water change afterwards. Currently I mix my saltwater in 5 gallon hedpaks which handles my bi-weekly 10% water changes. Is it ok to do a 5 gallon water change, then mix another 5 gallons and do another water change a couple of hours later or do I need to do it all at once?

You probably won't have any issue doing that, I'd get get something bigger like a brute trashcan or more buckets, something if possible, I wouldn't feel comfortable not being able to mix up at least 20% of my tank quickly in case of an emergency.

 

[Biokabe]

Ok guys I have a noob question. I'm running Chemiclean and plan on doing the recommended 20% water change afterwards. Currently I mix my saltwater in 5 gallon hedpaks which handles my bi-weekly 10% water changes. Is it ok to do a 5 gallon water change, then mix another 5 gallons and do another water change a couple of hours later or do I need to do it all at once?

It's really easy to overthink things when it comes to water changes.

The short answer to your question is that consecutive smaller water changes are not the same as a single water change, but you're not going to hurt anything by doing the change consecutively instead of all at once. It's not a habit you want to get into because it does waste salt, so long-term you're costing yourself more money. But as a one-off situation it's not a huge deal.

The reason it wastes water (and ultimately, salt) is as follows:

When you do a water change, you remove a portion of your tank's water and replace it with fresh water (in your case, 10% of your water). So an hour after you finish your water change, your tank consists of 90% old water, 10% new water. If you then do another water change two hours later, you'll pull out an equal fraction of new and old water (since water mixes fairly quickly, especially in a turbulent environment). So you'll pull out 9% of your old water, and 1% of your new water, and then replace it with 10% new water. After you fill it up, your tank will have 81% old water and 19% new water, so you're essentially throwing away 5% of the saltwater that you just mixed up.

5% of 10 gallons is only half a gallon, so I'd consider that an acceptable 'waste' for a one-time situation. But it's not a habit that I'd get into, because that 5% adds up over time.

For your own sanity, I'd recommend eventually either upgrading the size of your mixing container (preferable) or adding one or two more mixing containers to your arsenal so that you can do an emergency large water change if necessary. A 20g Brute can is pretty popular and would be a good fit for your tank size, but any food-safe container will work.