Dwarf gourami breeding / tank cleaning

Question
My male dwarf gourami built a bubble nest in my community tank 2 weeks ago amidst the leaves of a plant that reaches the surface. He's been chasing  the female, but I haven't seen any  sign of eggs being released yet.

How do I do water changes without destroying the nest? I normally change 25% of the water each week, but have left it for the last couple of weekends, as I didn't want to disturb the nest. On  the other hand I don't want the fish to  get ill...

Tank info:-
It's a 96 litre Juwel tank with only 7 fish in it (2 pearl gouramis,   2 dwarf gouramis, 1 angel  & 2 otocinclus, all adults).  Been set up for about 18 months. Has sponge filters (1 just for the bacteria, plus a nitrate removing filter, a charcoal filter & a weekly fine filter for removing most of the crud.  pH about 8.5 (hard water); no NH4 or NO2.

Thanks in  advance for your help,
Mattt.

Answer
Hi Mattt;

Change the water as usual and he will rebuild the nest as needed. It would be better to move him to a separate tank for breeding if you want to really let him get serious about it. Babies won't survive for long in a community tank and will cause turmoil and fighting. Out in nature they have a lot more space per fish to establish territory, protect young and chase rivals or enemies away. It's just too "close" in there to be safe and somebody could get hurt.   

Good Luck...

At Your Service;
Chris Robbins