Siporax and pH

[dust]

Please provide information on the best filter media for a sump. I tried the new Siporax, but it spiked the pH to a shocking 9.4, so I removed it immediately. What do you suggest? Only sponges?

 

[dw1305]

Hi all,

Please provide information on the best filter media for a sump. I tried the new Siporax, but it spiked the pH to a shocking 9.4, so I removed it immediately. What do you suggest? Only sponges?

You can use floating cell media, hydroleca or reasonably coarse sponge. Personally I'd stick with Siporax, now you've got it. I'm assuming you have soft water, so the pH rise doesn't reflect a large addition of acid, and they shouldn't effect pH once they are rinsed.

Cheers Darrel

 

[illumnae]

I've been using Siporax for almost a decade and haven't had any pH issues. It's supposed to be made from sintered glass which is chemically inert. I've used it in setups using ro water, tap water and even marine reef tanks

 

[dust]

I put the Siporax into a heavy-duty mixing tub, filled it with RO water and acid, and kept it circulating with a pump. It finally gave up and went back into the sump. It probably behaves differently in tap water, but in sterile water, a brand new batch can cause quite a few problems initially.

 

[dw1305]

Hi all,

I put the Siporax into a heavy-duty mixing tub, filled it with RO water and acid, and kept it circulating with a pump.

That should work.

.... It probably behaves differently in tap water, but in sterile water, a brand new batch can cause quite a few problems initially.

The issue isn't really with the Siporax, but with pH as a <"measurement">.

You can't meaningfully measure pH in RO water, because it doesn't start with any solutes and any addition of bases ("proton acceptors"), however small, will cause a rise in pH.

You can actually see this effect in reverse with the pH drop caused by dissolved CO2 in rainwater. There are "only" 425 ppm of CO2 in the atmosphere, but the 0.15% (of the 0.6 ppm of CO2 in solution) that dissolves as H2CO3 (and then disassociates into a proton H+ and HCO3- ions) is enough to drop the pH to pH 5.5.

Cheers Darrel