Cyno's Revenge

[haus]

There are signs of cyno in my tank again. I have battled it in the past and won, but it has come back for seconds. After testing the water quality, I believe that tap water may be the culprit. Ammonia = 0, Nitrites = 0, Nitrates = 0, PO4 = 0. The lights are on 9 hrs per day, and the fish are fed every other day. This leads me to believe that the cause is the use of tap water. I've used chemi-clean with success before, but I don't want to do it again. I haven't tested my tap water for PO4 before, but the water in the tank has 0. Is the difference between tap and RO/DI water going to be that significant as to stop the cyno?

[MT79]

Is the difference between tap and RO/DI water going to be that significant as to stop the cyno?

Its' hard to say exactly. There are many things in tap water, beside PO4, that could promote the growth of nuisance algaes/cyano. Have you ever checked the TDS of your tap water?

[haus]

No, and I don't have a TDS meter. I wonder if I take a water sample to the lfs, if they can check that. What are some of the other factors that promote cyno growth?

[melissfish]

i have been buying seawater for about 8 months and havent seen cyanos since, it also saves time as i dont have to mix the salt and water and i know the water is right first time. I used to mix tapwater and i had cyaNOS problems also it cost me more to buy thesalt than it does water

[seaham358]

No need for a TDS meter it only measures total disolved solids... Could be bad or good TDS, so no need to get a TDS for tap water. PO4 and nitrate are the 2 things you need to look for with cyno, PO4 beign the #1 problem. Not all PO4 can be measured with the test kits we use. If you have cyno you have some PO4 in the tank to feed it, you may not be able to detect it with the kits we use. Old bulbs can also help cyno grow as well as low flow.
RO/DI IMO is the best thing you could get for the tank. There is no way your tap water could be as pure as ro/di.
check your tap water for PO4 that would be my first step, if you have any at all then you should look into a ro/di unit.
Siphon out the cyno when you do your water changes, so not blow it areound the tank that only helps in spreading it... Good luck.