Raising .4 dKH in 1 water change is OKAY?

[BHD]

Hello everyone.

My tank is 100 gallons (75 display + 40 breeder sump). Currently my alk is 8.0 dKH according to Salifer test kit. I would like to change 20% of the total water every week. The dKH of the freshly mixed water is 10. So after I change the 20% of the total volume, the new Alk will be 8.4dKH.

I hope my math is correct. So I was wondering if raising .4dKH in one water change like that is Okay or too much for SPS to handle?

Thanks,
Bao

 

[Allmost]

it will be a BIT of a shock for them ... but not enough to cause damage from my experience.

it would be much better to do 2 smaller water changes ,... 10% each ? twice a week ? [I know its hard to go through it 2 times a week though]

 

[BHD]

thanks for the reply.

Yeah I have always been doing 10% wc weekly, dosing vinegar and running gfo. But few months ago I attempted to go the natural route by using Chaeto and water change only so I stopped dosing vinegar and stop running gfo. and its fishing season and I feed plenty of fish eggs to my fishes and corals, the fishes and corals love it. But after 2 months, I have hair algae everywhere. I went back to dosing vinegar and running gfo again for two months now but still can't kill the HA. So that's why I want to increase my water change to 20% weekly for a few months to combat those HA.

 

[dan-in-gr]

Hi, I change mine with .5 steps with my SPS only tank and have no problem. In fact BRS shows not to go over 1.4 dKh and .2 raise in pH per day.

This is from there website Reef Calculator: (note: for Soda Ash, other chemicals may have different rates).

INSTRUCTIONS

Fully dissolve the Soda Ash in RO/DI or distilled water per the packages instructions (2 cups per gallon of RO/DI water). Slowly add the solution to high flow areas of the tank and avoid directly blasting corals with the concentrated solution. Soda Ash will increase pH. Although this is temporary it is important to monitor pH during your initial dose and avoid raising the PH more than 0.20. Do not increase alkalinity levels more than 0.5meq/lt or 1.4 dKH per day. If necessary spread the suggested dose out and test between doses.

MIXING NOTES

When mixing the salts with the filtered water it is best to add a small portion at a time, shake the jug and add more so the salts don't clump up. If it does clump, float the jug in hot water to warm the fluid inside and it should dissolve easier. We recommend allowing the solution to rest at least a couple hours before use so the salts have a chance to fully dissolve.

 

[Allmost]

yea the couple of months of no gFO has made the po4 bond with ure rocks and sand ... it will take some time to get it all out and best way is to run GFO, blow the rocks and remove HA manually. and carbon dosing, and patience, and larger water changes.

good luck