hydrochloric acid in tank

Reefsareef · Jan 22, 2023

I was watching a video on YouTube about DIY reagents.
I have a KHD and use hydrochloric acid 0.1n.
I may of misheard him, but I'm sure he said. dosing the waste water back to tank would be completely harmless?

Anyone else agree or disagree?

Randy Holmes-Farley · Jan 22, 2023

Reefsareef said:
I was watching a video on YouTube about DIY reagents.
I have a KHD and use hydrochloric acid 0.1n.
I may of misheard him, but I'm sure he said. dosing the waste water back to tank would be completely harmless?

Anyone else agree or disagree?

Forget the acid (assuming it is not grossly contaminated) and think of it like adding a very small amount of zero alk seawater to your tank each day. Not a big deal. Just adds a tiny bit to your daily alk demand.

of course, tossing it out is also fine. Just causes a tiny salinity drop each day which can easily be offset by water changes.

Reefsareef · Jan 22, 2023

Randy Holmes-Farley said:
Forget the acid (assuming it is not grossly contaminated) and think of it like adding a very small amount of zero alk seawater to your tank each day. Not a big deal. Just adds a tiny bit to your daily alk demand.

of course, tossing it out is also fine. Just causes a tiny salinity drop each day which can easily be offset by water changes.

Thanks.
I have to go away for 12 weeks.
Although the wife is at home, she isn't able to carry out tank maintenance.
I was considering dosing the waste back to the tank. but also wouldn't have any water changes done

Randy Holmes-Farley · Jan 23, 2023

Reefsareef said:
Thanks.
I have to go away for 12 weeks.
Although the wife is at home, she isn't able to carry out tank maintenance.
I was considering dosing the waste back to the tank. but also wouldn't have any water changes done

is the tank being topped off for evaporation? How are alk and calcium being added?

Reefsareef · Jan 23, 2023

I have 50L storage for evaporation, I have an low level alarm and the wife will be able to top that up when needed.
I dose ATI Essentials for the daily

Randy Holmes-Farley · Jan 23, 2023

Reefsareef said:
I have 50L storage for evaporation, I have an low level alarm and the wife will be able to top that up when needed.
I dose ATI Essentials for the daily

If you choose to collect the waste, you can just put a small amount of salt in the top off to offset it, or if you keep the waste in the tank you can dose a very tiny bit more of the 2 part or put a bit of the alk part into the top off water.

How much waste per day (mL) and what is the tank volume?

We can determine how large each effect is in 12 weeks (salinity or alk).

Reefsareef · Jan 23, 2023

Waste would be 600ml a day and tank size is 1000L

Randy Holmes-Farley · Jan 23, 2023

Reefsareef said:
Waste would be 600ml a day and tank size is 1000L

Perfect.

The salinity drop to discarding the waste would be 50.4 L per 1000 L per 12 weeks, for a drop from 35 ppt to 33.2 ppt. Might be Ok to do nothing about it. But if you put the equivalent of the salt needed for 600 ml in each days top off (about 23 grams) then salinity will be quite close to normal when you return.

The alk drop each day from returning the water is a factor of (1000 L -0.6 L)/1000 L = 0.994. If the alk is 8 dKH each day, then the drop from adding the waste back is 0.005 dKH per day. Very small. Adding a tiny bit extra alk each day is likely not even needed (its only 0.4 dKH over the while 12 weeks), but you could think about adding a tiny bit more alk each day.

IMO, either way is OK without any corrections for 12 weeks.