ok so your levels are;
alk 3.5/meq.l(9-10dkh)
Ca+ 450
ph 8.0-8.5 (def get the monitor, is this the color range for your kit?)
the deal with ph is your swing, you want it to be less than 0.2(ex. 8.10 in the am then 8.30 max through the day). during photoperiods your ph should rise via photosynthesis(eats up CO2) and at night CO2 acumulates, as CO2 uptake reduces during nonphotoperiods resulting in acumulation of CO2 thus, ph decrease. with your kit, if that is the color range, you will not be able to tell what the swing is. if your tank is hitting 8.5 or possible above its likely your tank is low on CO2. this will also cause your cheato not to grow as CO2 is alga's main source of carbon, which is very much needed for grow. low CO2 levels usually result in big ph swings aswell and that is very stressful for on corals, especially with new additions--this may or may not be an issue as we dont know the exact ph. an example of wanted and unwanted levels; this is for change in ph effect,
ph 8.0
alk 4.0meq/l (11 dkh)
Ca+ 400ish
these are good--very normal
ph 8.5
alk 4.0
Ca+ 400ish
these are not good, entering non-biological precipitation ranges.
samething here but instead we will keep ph high and change Ca+/alk levels;
ph 8.5
alk 2.5(7dkh)
Ca+ 260ish
these are ok(hard to keep but ok) now with this ph(maybe around your current level) if you raise Ca+/alk around your current levels-
ph 8.5
alk 4.2(12 dkh)
Ca+ 410
these are not good and your at risk for non-biological precipitation(FYI if precipitation occurs your ph,Ca+ and alk will change).
with a ph of 8.5 higher levels of Ca+ and alk are not good.
these numbers are entering the non-biological precipitation range(causes Ca+ and alk to fall out of solution.) lower ph's keep things in solution. with lower ph's you can run Ca+ and alk levels on the high side of normal, with higher ph's you will want Ca+ and alk levels on the low side of normal ranges. your running everything on the high side of normal which is risky. with your alk and Ca+ levels if your ph is running 8.5 then you will want to bring the ph down some in the range of 8.2. or you could lower Ca+ and alk levels to the lower/mid ranges of normal.
if your swing is 8.0 to 8.5 then your going in and out of good and bad levels in regaurds to Ca+ and alk levels. so lets rule out low CO2 issues first, its monitor time
....still do the night and day time testing with your kit, might get lucky and see it fall in different color zones. with out a monitor using a kit with a color range indicating ph levels inbetween 8.0-8.5 you will not be able to rule out ph swings as an issue.
what are you dosing, everything. Ca+ sups/alk sups/buffers/anything and everything else?
on the light, i agree its not enough but even so softies should live unless your bulbs are too old and omitting mostly UV rays, how old are you bulb and how many hours is your photoperiod?
another thought is stray voltage- which usually doesnt effect fish much as they can move away/around electrical waves, unlike corals. do you have a voltage meter or multi tester handy? if not they are cheap, homedepot auto parts store....need one that has a setting for AC voltage (VAC).
so for now lets rule out these three possible issues;
1. ph swings---need a monitor here or more sensitive kits.
2. old light bulds and UV damage--just need to know how old the bulbs are..and if you have any fan blowing around the bubls while they are on.
3. stray voltage--just need to check with a voltage meter, cutting your finger and sticking it in the tank to check for shock dosent help unless you have alot of stray voltage. stray voltage may still be an issue even if you dont get a shock so testing with voltage tester or volt meter would be my suggestion.
