RTNing SPS

[jeffmr4]

I have a relatively small Acropora frag that has been rtning the past couple of days. I do about 20% water changes once per week and end up dosing for mg, ca and alkalinity. Mg usually drops to 1380 and I raise it to 1425, ca is usually 380 or so and I raise it to 421. Alkalinity can drop quite a bit. This week it was down to 6.4 from 8.5. As per BRS's instructions I am going up less than 1.4 dKh per day but I usually dose all in a day with the exception of the alkalinity. Salinity is 1.025 - 6, Temp. 78, pH 8.0, phosphate 0.00. I can't seem to get that up at all. If I feed I have an undesirable algae/bacteria that grows more so I haven't been feeding more.

Does anyone have any idea as to why the rtn has started and if so any suggestions for fixing it other than dipping it or fragging it?

Thank you in advance.

 

[cboltsd01]

You have no stability in your water parameters. Too many swings, especially in Alk. Are you hand dosing or using a doser?

 

[jeffmr4]

I wondered about that. I've been dosing like this for a while but consumption has gradually increased. I dose by hand. I would prefer not to get a doser but may have to. Its a 10 gallon tank with a 13 gallon sump for a total of 18 gallons after displacement.

 

[stephj03]

That’s a pretty small system to attempt SPS in. Hard not to get swings in a 20g SPS rig even with more gear.

Any possibility at all of increasing volume? Larger sump? Add a fuge?

How much consumption are you seeing? How much are you having to dose?