Water changes bad for reef?

[johnm92172]

I have a 50 gallon reef about a year old. I really slacked when it came to water changes, and the green hair algae really overtook the tank. According to Salifert's PO4 test kit, PO4 was zero. I tried Hanna's electronic test kit, and it read 1.0! Anyway, I started doing 15% water changes usually about every 3 days or so. Most of the hair is now gone, but im starting to see brown cyano starting to cover the sand and some of the rock. I use Instant Ocean Reef Crystals. Could it be the extra trace elements in the salt doing this? After changing 15% about 3 times, PO4 readings on the Hanna kit still shows .8.

[bertoni]

The water changes will add trace elements, if any are being consumed, and also a bit of fixed nitrogen (ammonia). I might cut back to 15% once a month, and work on the phosphate reading some other way. Water changes will work, but they will get very pricey. I'd start with some GFO, although lanthanum chloride will be cheaper if the problem is extensive.

[johnm92172]

The water changes will add trace elements, if any are being consumed, and also a bit of fixed nitrogen (ammonia). I might cut back to 15% once a month, and work on the phosphate reading some other way. Water changes will work, but they will get very pricey. I'd start with some GFO, although lanthanum chloride will be cheaper if the problem is extensive.

Well at the same time ive been using Seachem's phosguard and before that GFO, but it still shows that high reading.

[bertoni]

You probably will need to use more media, and change it frequently, at least for a while. GFO can be exhausted in a few hours with the phosphate level that high. That's why lanthanum chloride can save a fair amount of money.