Is my water change process stressing out my fish?

[squid row]

I have had two ick outbreaks in the last year, both times came after a water change so I am wondering if it is possible that I am doing it wrong.

What I do is mix up 35 gallons of saltwater with RO/DI and Reef Crystals to match the salinity in my DT.

I keep the new saltwater mix at the same temp as my DT and keep it circulating with two older fountain pumps. The water is mixed and kept in a clean, covered container until I am ready to use it.

To change the water I turn off the skimmer and return pump and drain out 10 - 15 gallons (72 gallon tank, 20 gallon sump) then slowly add in the new water at the same pace I took it out (use same syphon)

No big temp swings, parameters of the water are the same but two ick outbreaks after.

What am i doing wrong?

 

[MondoBongo]

you haven't eliminated ich from your tank.

it isn't related to the water changes.

ich has a defined lifecycle that includes a dormant period. get rid of the organism, and you will stop seeing recurrent infections.

https://www.thesprucepets.com/life-cycle-saltwater-ich-cryptocaryon-irritans-2924987

 

[Sk8r]

I drain the sump, then refill it with new water. Plenty enough to 'stress' the system, and no ich. It's coincidence, basically.

Ich is not stress-related, though it gets a better chance to infect if ph/alkalinity goes wonky (alk should be kept steady at about 8.3 ---which helps fish maintain a good slime coat. ) Outside of crashing the slime coat, there's not much about water that can hurt.

My take (whether or not you have an 'off' alkalinity) is that your tank is infested with ich (an animal) that lies in wait in the sandbed and attacks fish gills or body and embeds itself.

The best cure is to take your fish out to quarantine and run TTM (tank transfer : look it up in the Fish Disease forum on this site) to get them free of ich, then do not allow a fish into your tank for 72 days, which is sufficient time for the ich to starve to death without being able to reproduce (it takes a fish dinner for it to reproduce). Note: only fish need be removed. Ich can't use anything else.

A pain, but that will solve your problem.